I will discuss how to relate the entropy of BPSblack holes in AdS to counting of states in gaugetheory, presenting examples where this can besuccessfully done as well as examples where thisdoes not seem to work.LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1476709200860f4fa8f8746576b700e6f0fc931de1@sns.ias.edu DTSTART:20161017T130000Z DTEND:20161017T140000Z SUMMARY:Workshop on the Chaos, the SYK Model and AdS2, "New Results in the SYK Model" (Alexei Kitaev, Caltech) DESCRIPTION: LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:147672900016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20161017T183000Z DTEND:20161017T200000Z SUMMARY:High Energy Theory Seminar, "Strange Metals, Black Holes, and Graphene" (Subir Sachdev, Harvard University) DESCRIPTION:

States of quantum matter without quasiparticles can be more precisely characterized by their rapid approach to local thermal equilibrium: this is argued to happen in a shortest possible time of order (Planck’s constant)/((Boltmann’s constant)x(absolute temperature)). Black holes are physical systems which also equilibrate in this time, with the absolute temperature identified as the Hawking temperature. And this similarity is not a co-incidence: the Sachdev-Ye-Kitaev model of a “strange metal” without quasiparticle excitations, also turns out to be a theory of a black hole in 1+1 dimensional anti-de Sitter space. I will discuss a general formulation of a transport theory of states of matter without quasiparticle excitations, which was inspired by these black hole analogies. This formulation leads to experimental predictions, including some that agree well with recent observations on graphene.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1476795600860f4fa8f8746576b700e6f0fc931de1@sns.ias.edu DTSTART:20161018T130000Z DTEND:20161018T140000Z SUMMARY:Workshop on the Chaos, the SYK Model and AdS2, "Adding Space to the SYK Model" (Xiaoliang Qi, Stanford University) DESCRIPTION: LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:147682080007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20161018T200000Z DTEND:20161018T210000Z SUMMARY:Pheno & Vino Seminar, "Exploring the Weak Gravity Conjecture" (Matthew Reece, Harvard University) DESCRIPTION: LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1476889200860f4fa8f8746576b700e6f0fc931de1@sns.ias.edu DTSTART:20161019T150000Z DTEND:20161019T160000Z SUMMARY:Workshop on the Chaos, the SYK Model and AdS2, "Microscopic Model of Quantum Butterfly Effect: Out-of-time-order Correlators and Traveling Combustion Waves" (Lev Ioffe, Rutgers University) DESCRIPTION: LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1476899100ddcbf452bffff0a1f9a416202b44514a@sns.ias.edu DTSTART:20161019T174500Z DTEND:20161019T190000Z SUMMARY:Physics Group Meeting, "Entanglement Structure of Non-Equilibrium Steady States" (Brian Swingle, Stanford University) DESCRIPTION: LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:14769666003c11a39d4a3e680d3b72ff2b75cab2eb@sns.ias.edu DTSTART:20161020T123000Z DTEND:20161020T210000Z SUMMARY:PCTS Workshop, "Journey to the Center of the Bulk" DESCRIPTION:This workshop will unify two broad topics of recent interest, brought together by the AdS/CFT correspondence: the construction of novel probes of spacetime dynamics in gravity and string theory, and non-perturbative methods for constraining the space of unitary CFTs and theories of AdS quantum gravity. Through the lens of quantum chaos, entanglement dynamics and the conformal bootstrap at large central charge, the workshop aims to illuminate the structure of holographic CFTs and the mechanism of emergence of classical geometry.

LOCATION:Jadwin Hall, PCTS Seminar Room, Fourth Floor, Room 407 COMMENT:Please note that the workshop is fully subscribed and will be streamed live at http://www.kaltura.com/tiny/jxaqm URL:http://wwwphy.princeton.edu/pcts/Bulk2016/Bulk2016.html END:VEVENT BEGIN:VEVENT UID:1476993600c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20161020T200000Z DTEND:20161020T220000Z SUMMARY:Hamilton Colloquium Series, "Quantum Gravity and Quantum Chaos" (Stephen Shenker, Stanford University) DESCRIPTION:One hallmark of chaos is sensitive dependence to initial conditions, the “butterfly effect.” We will discuss recent advances in our understanding of the quantum butterfly effect and its connection to the quantum physics of black holes. We will discuss a universal bound on the rate of development of quantum chaos motivated by these developments. Then we will briefly describe recent work on a connection between the late time behavior of black holes and the dynamics of random matrices.

LOCATION:Jadwin Hall, Room A10 COMMENT:Host: Herman Verlinde - Tea at 3:30 p.m., Lounge Area outside of Jadwin A-10 URL: END:VEVENT BEGIN:VEVENT UID:14770530003c11a39d4a3e680d3b72ff2b75cab2eb@sns.ias.edu DTSTART:20161021T123000Z DTEND:20161021T210000Z SUMMARY:PCTS Workshop, "Journey to the Center of the Bulk" DESCRIPTION:This workshop will unify two broad topics of recent interest, brought together by the AdS/CFT correspondence: the construction of novel probes of spacetime dynamics in gravity and string theory, and non-perturbative methods for constraining the space of unitary CFTs and theories of AdS quantum gravity. Through the lens of quantum chaos, entanglement dynamics and the conformal bootstrap at large central charge, the workshop aims to illuminate the structure of holographic CFTs and the mechanism of emergence of classical geometry.

LOCATION:Jadwin Hall, PCTS Seminar Room, Fourth Floor, Room 407 COMMENT:Please note that the workshop is fully subscribed and will be streamed live at http://www.kaltura.com/tiny/jxaqm URL:http://wwwphy.princeton.edu/pcts/Bulk2016/Bulk2016.html END:VEVENT BEGIN:VEVENT UID:14771394003c11a39d4a3e680d3b72ff2b75cab2eb@sns.ias.edu DTSTART:20161022T123000Z DTEND:20161022T210000Z SUMMARY:PCTS Workshop, "Journey to the Center of the Bulk" DESCRIPTION:This workshop will unify two broad topics of recent interest, brought together by the AdS/CFT correspondence: the construction of novel probes of spacetime dynamics in gravity and string theory, and non-perturbative methods for constraining the space of unitary CFTs and theories of AdS quantum gravity. Through the lens of quantum chaos, entanglement dynamics and the conformal bootstrap at large central charge, the workshop aims to illuminate the structure of holographic CFTs and the mechanism of emergence of classical geometry.

LOCATION:Jadwin Hall, PCTS Seminar Room, Fourth Floor, Room 407 COMMENT:Please note that the workshop is fully subscribed and will be streamed live at http://www.kaltura.com/tiny/jxaqm URL:http://wwwphy.princeton.edu/pcts/Bulk2016/Bulk2016.html END:VEVENT BEGIN:VEVENT UID:147733380016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20161024T183000Z DTEND:20161024T200000Z SUMMARY:High Energy Theory Seminar, "Topological String, Spectral Theory and Painlevé Equations" (Alba Grassi, ICTP, Trieste) DESCRIPTION:In this talk I will review some aspects of a recently proposed duality between topological string on toric Calabi-Yau manifolds and the spectral theory of trace class operators. I will discuss the relation between this construction and Painlevé equations which can be used to prove the duality in a 4-dimensional limit. In addition I will apply these results to study Seiberg-Witten theory in the 4-dimensional self-dual omega background and show that this theory admits a dual description in terms of an ideal Fermi gas.

LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:147742560007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20161025T200000Z DTEND:20161025T210000Z SUMMARY:Pheno & Vino Seminar, "Cornering Natural SUSY at the LHC" (David Shih, Rutgers University) DESCRIPTION:We derive the latest constraints on various simplified models of natural SUSY with light higgsinos, stops and gluinos, using a detailed and comprehensive reinterpretation of the most recent 13 TeV ATLAS and CMS searches with $\sim 15$~fb$^{-1}$ of data. We discuss the implications of these constraints for fine-tuning of the electroweak scale. A key aspect of this work is an improved calculation of the tuning measure (including two-loop effects, a proper treatment of UV vs.~IR masses, and threshold effects), which significantly relaxes the naturalness bounds on the stop and gluino masses. Despite this, natural SUSY is under pressure from the LHC.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1477600200c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20161027T203000Z DTEND:20161027T220000Z SUMMARY:Hamilton Colloquium Series, "The Search for Quantum Anomalous Hall Insulators" (David Vanderbilt, Rutgers University) DESCRIPTION:The quantum Hall effect, discovered 35 years ago, is a bizarre phenomenon in which a 2D gapped system can nevertheless carry a current. Moreover, the transverse conductivity of the system is precisely quantized in units of e^2/h. Unfortunately, this behavior requires a strong perpendicular magnetic field, and has only been observed at low temperatures. Work of Haldane in 1988 raised the possibility that similar physics could be observed in two-dimensional magnetic systems without any external magnetic field, and potentially at much higher temperatures. Such a system is known as a “quantum anomalous Hall” (QAH) or “Chern” insulator.

In this talk I will introduce the essential physics of the QAH effect, provide a tutorial on its mathematical description in terms of Berry phases, and briefly describe recent successes in finding low-temperature realizations. I will then review some of our own recent work in which we propose the deposition of atoms with strong spin-orbit interactions onto the surfaces of magnetic insulators as a promising route toward the synthesis of higher-temperature QAH systems.

I will introduce a technique in studying the analytic structure of perturbative S-matrix of QFTs. The main idea is to associate Feynman integrals to objects in a projective space: polytopes and hypersurfaces. At one loop, this reveals a universal structure for all possible Feynman integrals (in particular, including one-loop amplitudes in any QFTs), and gives rise to two simple algebraic algorithms to determine the integrals (as functions of the kinematics). I will also comment on the generalization to higher loop levels.

LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:147793860016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20161031T183000Z DTEND:20161031T200000Z SUMMARY:High Energy Theory Seminar, "A 1d Topological Sector of 3d SCFTs from Supersymmetric Localization" (Silviu Pufu, Princeton University) DESCRIPTION:3d {\cal N} = 4 SCFTs have two protected topological sectors, one associated to the Higgs branch and one to the Coulomb branch. I will use supersymmetric localization to derive a Lagrangian description for the 1d sector associated with the Higgs branch, in the case in which the 3d SCFT has a UV Lagrangian description involving vector multiplets and hypermultiplets. The 1d Lagrangian is that of a topological gauged quantum mechanics. This 1d theory can be used to calculate n-point correlation functions of certain linear combinations of Higgs branch operators in the SCFT, and in particular it can be used to calculate the structure constants of the Higgs branch operator algebra.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:147828150016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20161104T174500Z DTEND:20161104T193000Z SUMMARY:High Energy Theory Seminar, "The Ryu-Takayanagi Formula and Extremal Surfaces" (Xi Dong, Member, School of Natural Sciences, IAS) DESCRIPTION:The Ryu-Takayanagi formula and its quantum-corrected version are useful in understanding many aspects of quantum gravity such as subregion duality, emergence of the radial direction, and the generalized second law. In this talk, I will first present a classical argument showing that in the large N limit the von Neumann entropy of a boundary region is given on the extremal surface in the presence of higher derivative corrections, by extremizing the entropy functional among all surfaces homologous to the boundary region. I will then show that all 1/N corrections are systematically obtained by considering the quantum extremal surface, defined by extremizing the generalized entropy which includes the bulk entropy. This is an extension of the Faulkner-Lewkowycz-Maldacena proposal and was conjectured by Engelhardt and Wall. A byproduct of these arguments is a proof of the Ryu-Takayanagi formula without assuming any replica symmetry of the dominant bulk replica solution. I will also mention the notion of "modular extremal surfaces" and use it to refine subregion duality and bulk reconstruction in AdS/CFT.

LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:147854700016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20161107T193000Z DTEND:20161107T210000Z SUMMARY:High Energy Theory Seminar, "Towards Finding All Elliptically Fibered Calabi-Yau Threefolds" (Daniel S. Park, Rutgers University) DESCRIPTION:I will review the efforts made towards approaching string universality in six dimensions and report recent "cartographic" developments on exploring the landscape of six-dimensional string vacua. A working conjecture is that all six-dimensional string vacua can be constructed in F-theory, which leads to the problem of classifying all elliptically fibered Calabi-Yau threefolds. I will present progress on classifying all the four-manifolds that can be used as a base of such threefolds.LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:147863880007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20161108T210000Z DTEND:20161108T220000Z SUMMARY:Pheno & Vino Seminar, "Can the Baryon Asymmetry Arise from Initial Conditions?" (Gordon Krnjaic, Perimeter Institute) DESCRIPTION:

In this talk, I'll quantify the challenge of explaining the baryon asymmetry using initial conditions in a universe that undergoes inflation. Contrary to lore, such an explanation is possible if net B−L number is stored in a light bosonic field with hyper-Planckian initial displacement and a delicately field velocity prior to inflation. However, such a construction may require extremely tuned couplings to ensure that this asymmetry is viably communicated to the Standard Model after reheating; the large field displacement required to overcome inflationary dilution must not induce masses for Standard Model particles or generate dangerous washout processes. While these features are inelegant, this counterexample nonetheless shows that there is no theorem against such an explanation. I'll also comment on potential observables in the double β-decay spectrum and on model variations that may allow for more natural realizations.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1478717100ddcbf452bffff0a1f9a416202b44514a@sns.ias.edu DTSTART:20161109T184500Z DTEND:20161109T200000Z SUMMARY:Physics Group Meeting, "The Weak Gravity Conjecture: Variations and Applications" (Matt Reece, Harvard University) DESCRIPTION: LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1478721600c0eb0c5583bc95fa859636a4e3306938@sns.ias.edu DTSTART:20161109T200000Z DTEND:20161109T210000Z SUMMARY:High Energy Physics Seminar, "Warm Dark Matter Cosmologies: In Theory and Simulations" (Sinziana Paduroiu, UNIGE) DESCRIPTION:Warm dark matter models are a viable alternative to the cold dark matter models challenged by many recent observations (e.g. dwarf galaxies, pure-disk galaxies, matter distribution in voids) and by the narrowed detection limits. I will review some theoretical assumptions made in describing the properties and behavior of different WDM candidates (in a wide mass range) and discuss the constraints from simulation results in the astrophysical contexts at both large and small scales.The intrinsic properties of WDM particles, strongly dependent on the assumed particle model and production mechanism, imprint a distinct signature on the structure formation and evolution. Using N-body cosmological simulations I will show that the structure formation mechanism in WDM is qualitatively different than in the CDM scenario and more complex than originally assumed - a 'hybrid' between 'top-down' and 'bottom-up' clustering on multiple scales - depending locally on the morphology of the analyzed region and globally on the free streaming length of the simulated particle. On smaller scales, the properties of WDM particles influence the shape and outlook of halos - caustics and shells and their internal structure - density and phase space density profiles. I will also comment on the technical aspects in simulating WDM and describe possible observational tests for distinguishing between dark matter models.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:14788008002b4033cbdee53a3f197d4bc51f767750@sns.ias.edu DTSTART:20161110T180000Z DTEND:20161110T193000Z SUMMARY:Special Pheno & Vino Seminar, "A New, Cosmological Solution of the Hierarchy Problem" (Nima Arkani-Hamed, Institute for Advanced Study) DESCRIPTION: LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1478811600c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20161110T210000Z DTEND:20161110T230000Z SUMMARY:Hamilton Colloquium Series, "The Dark Ages of Dark Matter" (Neal Weiner, New York University) DESCRIPTION:The search for dark matter is among the most challenging in particle physics, because even the question of how to look for it relies on an idea of what it is. The past decade has brought tremendous new data constraining the most popular scenario - the Weakly Interacting Massive Particle or WIMP. We will consider the implications for this new data and the prospects for discovery as experiments such as XENON and LUX reach maturity. As the WIMP has become increasingly constrained, researchers are looking into other directions, including the axion, but many other scenarios as well. New ideas have gone not just to what Dark Matter might be, but how we might look for it. I will discuss how this new “dark age” is unleashing tremendous creativity in answering that question, and how the next decade may be very different, but a very exciting time for dark matter searches.

LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:147888990016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20161111T184500Z DTEND:20161111T200000Z SUMMARY:High Energy Theory Seminar, "An Investigation of AdS2 Backreaction and Holography" (Thomas Mertens, Princeton University) DESCRIPTION:In this talk, I will discuss the Jackiw-Teitelboim model in 2d dilaton gravity in a holographic context. After deriving the boundary time reparametrization equation and the holographic stress tensor, I will demonstrate that these can be obtained from an effective boundary model. Within that description, the commutator of matter fields at large time separation agrees with a gravitational shock wave interaction. One-loop quantum effects in the bulk, when combined with the above results, allow for a model describing an evaporating black hole in AdS2. Based on arXiv:1606.03438.

LOCATION:Jadwin Hall, Room A06 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:147915180016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20161114T193000Z DTEND:20161114T210000Z SUMMARY:High Energy Theory Seminar, "Symmetry Enriched Emergent U(1) Gauge Theories" (Senthil Todadri, Massachusetts Institute of Technology) DESCRIPTION:Phases of quantum many particle systems can have low energy effective field theoretic descriptions in terms of gauge theories in their deconfined phase.

Such emergent gauge theories play a central role in modern theoretical work in condensed matter physics. In the presence of global symmetry many such phases - with the same emergent gauge structure - can be sharply distinguished. I will describe some of our work elaborating this in the specific context of free U(1) gauge theory in 3+1 space-time dimensions in the presence of time reversal and SO(3) global symmetries.

Precision gauge coupling unification is one of the primary quantitative successes of low energy or split supersymmetry. Preserving this success puts severe restrictions on possible matter and gauge sectors that might appear at collider-accessible energies. In this work we enumerate new gauge sectors which are compatible with unification, consisting of horizontal gauge groups acting on vector-like matter charged under the Standard Model. Interestingly, almost all of these theories are in the supersymmetric conformal window at high energies and confine quickly after the superpartners are decoupled. For a range of scalar masses compatible with both moderately tuned and minimally split supersymmetry, the confining dynamics happen at the multi-TeV scale, leading to a spectrum of multiple spin-0 and spin-1 resonances accessible to the LHC, with unusual quantum numbers and striking decay patterns.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:147932280002f1b40565bc473810bbdad8ef595389@sns.ias.edu DTSTART:20161116T190000Z DTEND:20161116T200000Z SUMMARY:Particle Astrophysics Seminar, "A high-resolution CMOS imaging detector for the search of neutrinoless double beta decay in Se-82" (Alvaro Chavarria, The University of Chicago) DESCRIPTION:The detection of neutrinoless double beta decay is the only known avenue to establish that neutrinos are Majorana fermi-ons, as opposed to Dirac fermions. We propose to develop high-resolution solid-state imaging devices from amorphous selenium evaporated on a complementary metal-oxide-semiconductor (CMOS) active pixel array for the search of the neutrinoless double beta decay of Se-82. We argue that a large array of these devices could have very low backgrounds, possibly reaching 1E-7/(kg y) in the neutrinoless decay region of interest, as it may be required for the full exploration of the neutrinoless double beta decay parameter space.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1479416400c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20161117T210000Z DTEND:20161117T223000Z SUMMARY:Hamilton Colloquium Series, "Topological Quantum Matter" (F. Duncan Haldane, Princeton University) DESCRIPTION:The laws of quantum mechanics have been known for nearly a century, and have passed every test that has been made of them. But knowing them does not mean that we understand all that they permit.

Einstein noticed that a key prediction of quantum mechanics is that it permits states with what is now called long-range “entanglement;” in his “second biggest mistake,” he thought that this would not be seen experimentally, thus falsifying quantum mechanics.

In recent years, it has gradually been realized that many strange classes of condensed matter can occur, which have robust unexpected exotic properties. Their “quantum entanglement” has turned out to be a key feature, suggesting applications to “quantum computing.” Their quantum states can be classified as being “topologically non-trivial,” distinct from “topologically-trivial” matter that can in principle be continuously evolved from widely-separated atoms. I will describe some of the simplest examples that led to this new understanding.

One of the many remarkable properties of conformal field theory in two dimensions is its connection to algebraic geometry. Since every compact Riemann surface is a projective algebraic curve, many constructions of interest in physics (which a priori depend on the analytic structure of the spacetime) can be formulated in purely algebraic language. This opens the door to interesting generalizations, obtained by taking another choice of field: for instance, the p-adics. We generalize the AdS/CFT correspondence according to this principle; the result is a formulation of holography in which the bulk geometry is discrete--the Bruhat-Tits tree for PGL(2,Q_p)--but the group of bulk isometries nonetheless agrees with that of boundary conformal transformations and is not broken by discretization. We suggest that this forms the natural geometric setting for tensor networks that have been proposed as models of bulk reconstruction via quantum error correcting codes; in certain cases, geodesics in the Bruhat-Tits tree reproduce those constructed using quantum error correction. Other aspects of holography also hold: Standard holographic results for massive free scalar fields in a fixed background carry over to the tree, whose vertical direction can be interpreted as a renormalization-group scale for modes in the boundary CFT. Higher-genus bulk geometries (the BTZ black hole and its generalizations) can be understood straightforwardly in our setting, and the Ryu-Takayanagi formula for the entanglement entropy appears naturally.

LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148036140016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20161128T193000Z DTEND:20161128T210000Z SUMMARY:High Energy Theory Seminar, "Correlation Functions in Superconformal Field Theories" (Jaume Gomis, Perimeter Institute) DESCRIPTION:We discuss the exact determination of correlation functions of local operators in four-dimensional N=2 superconformal field theories.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148044420016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20161129T183000Z DTEND:20161129T193000Z SUMMARY:High Energy Theory Seminar, "Non-Relativistic Scale Anomalies and Geometry" (Igal Arav, Tel Aviv University) DESCRIPTION:I will discuss the coupling of non-relativistic field theories to curved spacetime, and develop a framework for analyzing the possible structure of non-relativistic (Lifshitz) scale anomalies using a cohomological formulation of the Wess-Zumino consistency condition. I will compare between cases with or without Galilean boost symmetry, and between cases with or without an equal time foliation of spacetime. In 2+1 dimensions with a dynamical critical exponent of z=2, the absence of a foliation structure allows for an A-type anomaly in the Galilean case, but also introduces the possibility of an infinite set of B-type anomalies. I will also derive Ward identities for flat space correlation functions in Lifshitz field theories, and develop a method for calculating Lifshitz anomaly coefficients from these correlation functions using split dimensional regularization.

LOCATION:Jadwin Hall, PCTS Seminar Room 407, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148045320007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20161129T210000Z DTEND:20161129T220000Z SUMMARY:Pheno & Vino Seminar, "ETHOS - From Dark Particle Physics to the Matter Distribution of the Universe and Beyond" (Francis-Yan Cyr-Racine, Harvard University) DESCRIPTION:The fundamental properties of dark matter can affect structure formation in our Universe in subtle ways. Unfortunately, many dark matter theories make similar predictions for how structure assembles on large and small scales, leading to a large degeneracy in model space. Motivated by this, we formulate an effective theory of structure formation (ETHOS) that enables cosmological structure formation to be computed in a vast array of microphysical model of dark matter physics. This framework maps the detailed microphysical theories of particle dark matter interactions into the physical effective parameters that shape the linear matter power spectrum and the self-interaction transfer cross section of non-relativistic dark matter. These are the input to structure formation simulations, which follow the evolution of the cosmological and galactic dark matter distributions. These effective parameters in ETHOS allow the classification of dark matter theories according to their structure formation properties rather than their intrinsic particle properties, paving the way for future simulations to span the space of viable dark matter physics relevant for structure formation. We discuss how this framework can help understanding how dark matter microphysics affects structure formation on small scales.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1480531500ddcbf452bffff0a1f9a416202b44514a@sns.ias.edu DTSTART:20161130T184500Z DTEND:20161130T200000Z SUMMARY:Physics Group Meeting, "Quantum Mechanics with Noncommutative Amplitudes" (Greg Moore, Rutgers University) DESCRIPTION:I will fill in a few details concerning part three of my talk at Natifest.

LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1480626000c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20161201T210000Z DTEND:20161201T223000Z SUMMARY:Hamilton Colloquium Series, "Statistical Mechanics, Localization and Periodically Driven Quantum Systems" (Shivaji Sondhi, Princeton University) DESCRIPTION:The statistical mechanics of equilibrium systems is characterized by two fundamental ideas: that closed systems approach a late time thermal state and that of phase structure wherein such late time states exhibit singular changes as various parameters characterizing the system are changed. Recent progress has established generalizations of these ideas which apply to periodically driven, or Floquet, closed quantum systems. I will describe this progress, which centrally uses other recent advances in our understanding of many body localization. I will describe how it has resulted in the discovery of entirely new phases such as the π-spin glass/Floquet time crystal which exist only in driven quantum systems.

LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148070430016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20161202T184500Z DTEND:20161202T194500Z SUMMARY:High Energy Theory Seminar, "p-adic AdS/CFT" (Steve Gubser, Princeton University) DESCRIPTION:I will give a first-principles introduction to p-adic numbers and p-adic AdS/CFT. p-adic numbers are an alternative to the real numbers, and they have a hierarchical structure which lends itself naturally to a holographic construction. The bulk dual to a p-adic boundary is the so-called Bruhat-Tits tree, an infinite regular graph. A bulk-boundary correspondence can be set up starting from a classical action in the bulk, and correlation functions exhibit properties surprisingly similar to the ones derived in standard AdS/CFT. The ultrametricity of the p-adic numbers implies some simplifications of both the four-point function and the operator product algebra. I will also review a few results in p-adic field theory, both perturbative and non-perturbative.

LOCATION:Jadwin Hall, PCTS Seminar Room 407, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1481135400b31101ca51842404638db21f81d7f7fe@sns.ias.edu DTSTART:20161207T183000Z DTEND:20161207T193000Z SUMMARY:Special Seminar, "A Quantum Gas of Polar KRb Molecules in an Optical Lattice" (Jacob Covey, University of Colorado) DESCRIPTION:Ultracold polar molecules allow for investigation of quantum-state-controlled chemistry as well as strongly correlated many-body dynamics. After the first realization of polar molecules in the quantum regime, chemical reactions immediately became apparent in our KRb system. Upon obtaining a detailed understanding of the chemical reaction processes near absolute zero, we loaded our molecules in optical lattices that suppressed molecular reaction loss. In doing so, we were able to observe many-body spin dynamics between molecules pinned in a deep lattice, even though the filling fraction of the molecules was only ~5%. We have recently performed a thorough investigation of the molecule creation process in an optical lattice, and consequently improved our filling fraction to ~30% by preparing and overlapping Mott and band insulators of the initial atomic gases. This improvement realizes a fully connected quantum gas of polar molecules for the investigation of non-equilibrium, many-body spin dynamics. More recently, we switched to a second generation KRb apparatus that will allow application of large, stable electric fields as well as high-resolution addressing and detection of polar molecules in optical lattices. I will present our work on molecule creation in a three-dimensional optical lattice and the corresponding increase in the molecular filling fraction, as well as the status and direction of the second generation apparatus.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:14812218003e515b3953dede8982a0f0745ec754b1@sns.ias.edu DTSTART:20161208T183000Z DTEND:20161208T193000Z SUMMARY:Astroparticle Seminar, "Searching for Dark Matter with the DEAP-3600 Experiment" (Pietro Giampa, Queen's Universith) DESCRIPTION:DEAP-3600 is a single phase liquid argon (LAr) dark matter experiment, located 2 km underground at SNOLAB, in Sudbury, Ontario. The detector has 1 tonne fiducial mass of LAr. The target sensitivity to spin-independent scattering of 100 GeV WIMPs is 10^{−46} cm^{2}. The DEAP-3600 background target is < 1 background events in the WIMP region of interest in 3 tonne-years. The strategies to achieve this background are pulse shape discrimination to mitigate electron recoils, ultra-low radioactive materials for detector construction to reduce neutron and alpha backgrounds, and in-situ sanding of the acrylic vessel to mitigate radon exposure of surfaces during construction and fabrication. The WIMP search run began in 2016. This presentation gives an overview of the DEAP-3600 experiment and reports on recent results.

http://www.sno.phy.queensu.ca/group/

In this talk I will argue that a systematic classification of 4d N=2 superconformal field theories is possible through a careful analysis of the geometry of their Coulomb branches. I will carefully describe this general framework and then carry out the classification explicitly in the rank-1, that is one complex dimensional Coulomb branch, case. We find that the landscape of rank-1 theories is still largely unexplored and make a strong case for the existence of many new rank-1 SCFTs, almost doubling the number of theories already known in the literature. The existence of 4 of them has been recently confirmed using alternative methods and others have an enlarged N=3, supersymmetry.

LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1481230800c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20161208T210000Z DTEND:20161208T223000Z SUMMARY:Hamilton Colloquium Series, "The Path to CP Violation: Remembering Val Fitch and Jim Cronin in Princeton" (A. J. Stewart Smith, Princeton University) DESCRIPTION:

Within the past year and a half we have lost Val Fitch and Jim Cronin, two of Princeton’s greatest physicists. Their 1964 discovery of CP Violation in the decays of the long-lived neutral K meson, referred to at the time as “the Princeton Effect,” was a complete surprise, right out of the blue, that defied any and all explanation. The mystery was solved 37 years later when experiments at Stanford and Tsukuba, Japan observed CP violation in the B meson system, conclusively confirming the bold and prescient proposal of Kobayashi and Maskawa, put forward in 1973 when only three quarks were known, that CP violation would occur “naturally” in a 6-quark world. All measurements to date agree with this simple picture, in which CP violation results from interference between two amplitudes related by a single complex phase in the quark couplings.

In cosmology, however, the CP puzzle lives on as strong as ever! The “Princeton effect” pointed the way to Sakharov’s observation that CP violation is necessary to explain the disappearance of antimatter from the early universe, but is ten billion times too small. So paradoxically, we understand very well a tiniest manifestation of CP violation, but not at all the gigantic effect that allows our universe to exist.

In this talk, I’d like to pay tribute to Val and Jim with a personal and Princeton-centric account of the remarkable experiences and serendipities that drew these remarkable people together to make one of the most profound discoveries in particle physics. Their magic collaboration lasted less than two years, but their names will always be linked together in legend.

I will briefly review our current experimental knowledge of dark matter and then discuss recent developments in model building. In particular I will show that dark matter can be a thermal relic exponentially lighter than the weak scale without being exponentially weakly coupled. I will discuss concrete examples of light thermal dark matter with sizable self-interactions and observable couplings to the Standard Model. The focus will be on how minimal deformations of the WIMP paradigm produce vastly different phenomenological consequences.

LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148131360043df5baefea46fbbbb6683d0aeb87041@sns.ias.edu DTSTART:20161209T200000Z DTEND:20161209T210000Z SUMMARY:Special High Energy Physics Seminar, "An Inclusive and Generic Search for Supersymmetry in the Multijet + Missing Momentum Final State Performed on pp Collision Data Collected with the CMS Detector" (Jack Bradmiller-Feld, University of California, Santa Barbara) DESCRIPTION:For the past two years, the LHC has collided protons at a record-high center-of-mass energy of 13 TeV. This time has provided an opportunity to search for beyond standard model particles at the TeV scale, including those predicted by supersymmetry, with unprecedented sensitivity. I will briefly discuss some of the upgrades performed in preparation for the latest LHC runs, then present an overview of a generic search for strongly-produced supersymmetric particles in pp collisions in the multijet + missing transverse momentum final state. The data sample corresponds to 12.9 fb-1 recorded by the CMS experiment in 2016. I will review the theoretical and experimental motivation for this search, then describe some of the central challenges of the analysis. Finally, I will summarize the results, and look ahead to possible directions for this and similar searches in the coming years.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148157100016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20161212T193000Z DTEND:20161212T210000Z SUMMARY:High Energy Theory Seminar, "Bosonization in Two and Three Dimensions and Spin Structures" (Anton Kapustin, California Institute of Technology) DESCRIPTION:I will explain in examples how to incroporate the dependence on spin structure in fermionic lattice models. In two dimensions, I show to construct a spin-TQFT out of a superalgebra. In three dimensions, it turns out that fermionic lattice models are related to bosonic models with a global 1-form symmetry. This bosonization statement can be used to classify Symmetry Protected Topologicall phases of fermions.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148166280007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20161213T210000Z DTEND:20161213T223000Z SUMMARY:Pheno & Vino Seminar, "Visible Signatures of Dark Matter at the LHC" (Eder Izaguirre, Perimeter Institute) DESCRIPTION:I discuss well-motivated examples where Dark Matter production at the LHC can leave its imprint through striking visible signatures in addition to missing energy.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1481837400c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20161215T213000Z DTEND:20161215T230000Z SUMMARY:Hamilton Colloquium Series, "Building a Quantum Computer, Atom by Atom" (Christopher Monroe, University of Maryland) DESCRIPTION:Laser-cooled and trapped atomic ions are standards for quantum information science, acting as qubits with unsurpassed levels of quantum coherence while also allowing near-perfect measurement. When qubit state-dependent optical forces are applied to a collection of ions, their Coulomb interaction is modulated in a way that allows entanglement operations that form the basis of a quantum computer. Similar forces allow the simulation of quantum magnetic interactions, and recent experiments have implemented tunable long-range interacting spin models with up to 25 trapped ions, the largest collection of interacting qubits yet demonstrated. Scaling to even larger numbers can be accomplished by coupling trapped ion qubits to optical photons, where entanglement can be formed over remote distances for applications in quantum communication, quantum teleportation, and distributed quantum computation. By employing such a modular and reconfigurable architecture, it should be possible to scale up ion trap quantum networks to useful dimensions, for future quantum applications that are impossible using classical processors.

LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148399020016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170109T193000Z DTEND:20170109T203000Z SUMMARY:High Energy Theory Seminar, "Half hour talk + discussion on " Bubbling Geometries for AdS2 × S2"" (Oleg Lunin, SUNY at Albany) DESCRIPTION:Talk based on https://arxiv.org/abs/1507.06670

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:14847588002e49f77ffbd5fe82cff674012f89977d@sns.ias.edu DTSTART:20170118T170000Z DTEND:20170118T180000Z SUMMARY:Bootstrap Collaboration Online Seminar, "Analytic Functionals for the Conformal Bootstrap and Flat Space Scattering" (Dalimil Mazac, Perimeter Institute) DESCRIPTION: LOCATION:Viewing Location: PCTS seminar room, Jadwin Hall, 4th floor COMMENT: URL:http://indico.cern.ch/event/598882/ END:VEVENT BEGIN:VEVENT UID:14854554002f2854cafd226ffe65c947440fefbd09@sns.ias.edu DTSTART:20170126T183000Z DTEND:20170126T200000Z SUMMARY:Physics Seminar, "Basics of AC Signal Processing and the Fluctuation-dissipation Theorem" (Ken Van Tilburg, Member, School of Natural Sciences, IAS; New York University) DESCRIPTION: LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:14854554006c6d2cd594795ee1eb621c27faaf1e5d@sns.ias.edu DTSTART:20170126T183000Z DTEND:20170126T200000Z SUMMARY:The Precision Frontier Seminar, "Basics of AC Signal Processing and the Fluctuation-dissipation Theorem" (Ken Van Tilburg, Member, School of Natural Sciences, IAS; New York University) DESCRIPTION: LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148580460016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170130T193000Z DTEND:20170130T203000Z SUMMARY:High Energy Theory Seminar, "Tensor Models and Melonic Large N Limits" (Igor Klebanov, Princeton University) DESCRIPTION:We review the double line notation for the Feynman diagram expansion of N by N matrix models. In the ‘t Hooft large N limit only the planar diagrams survive, and the dual graphs may be thought of as discretized random surfaces. We proceed to theories where the dynamical degrees of freedom are rank-3 tensors with distinguishable indices, each of which takes N values. Their Feynman diagrams may be drawn using colored triple lines (red, blue, green), while the dual graphs are made out of tetrahedra glued along their triangular faces. As shown by Gurau, Rivasseau and others, such theories possess a special solvable large N limit dominated by the “melon” diagrams. Following Witten’s work we discuss quantum mechanical models of fermionic rank-3 tensors and their similarity with the Sachdev-Ye-Kitaev disordered model. We then use the large N Schwinger-Dyson equations to study the conformal dimensions of certain composite operators. Gauging the global symmetry in the quantum mechanical models removes the non-singlet states; therefore, one can search for their well-defined gravity duals. We note that the models possess a vast number of gauge-invariant operators involving higher powers of the tensor field. Finally, we discuss similar models of a commuting rank-3 tensor in dimension d. While the quartic interaction is not positive definite, we study the large N Schwinger-Dyson equations and show that their solution is consistent with conformal invariance.

LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1485974700ddcbf452bffff0a1f9a416202b44514a@sns.ias.edu DTSTART:20170201T184500Z DTEND:20170201T200000Z SUMMARY:Physics Group Meeting, "The Lightcone Bootstrap and the Spectrum of the 3d Ising CFT" (David Simmons-Duffin, Member, School of Natural Sciences, IAS) DESCRIPTION:I will review the lightcone bootstrap and explain how it canbe used to describe analytically some new numerical results for the 3dIsing CFT.LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:14860602006c6d2cd594795ee1eb621c27faaf1e5d@sns.ias.edu DTSTART:20170202T183000Z DTEND:20170202T200000Z SUMMARY:The Precision Frontier Seminar, "Searches for Light Scalar Particles" (Ken Van Tilburg, Member, School of Natural Sciences, IAS; New York University) DESCRIPTION: LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148640940016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170206T193000Z DTEND:20170206T210000Z SUMMARY:High Energy Theory Seminar, "Towards a Theory of the QCD String" (Sergei Dubovsky, New York University) DESCRIPTION: LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148650120007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20170207T210000Z DTEND:20170207T220000Z SUMMARY:Pheno & Vino Seminar, "Soft-Collinear Supersymmetry" (Tim Cohen, University of Oregon) DESCRIPTION:

Soft-Collinear Effective Theory (SCET) is a framework for modeling the infrared structure of theories whose long distance behavior is dominated by soft and collinear divergences. This paper demonstrates that SCET can be made compatible with supersymmetry (SUSY). Explicitly, the effective theory for ?=1 SUSY Yang-Mills is constructed and shown to be consistent. For contrast, arguments are given that chiral SUSY theories with Yukawa couplings, specifically the single flavor Wess-Zumino model, are incompatible with the collinear expansion. SCET is formulated by expanding fields along a light-like direction and then subsequently integrating out degrees-of-freedom that are away from the light-cone. Defining the theory with respect to a specific frame obfuscates Lorentz invariance -- given that SUSY is a space-time symmetry, this presents a possible obstruction. The cleanest language with which to expose the congruence between SUSY and SCET requires exploring two novel formalisms: collinear fermions as two-component Weyl spinors, and SCET in light-cone gauge. By expressing SUSY Yang-Mills in "collinear superspace", a slice of superspace derived by integrating out half the fermionic coordinates, the light-cone gauge SUSY SCET theory can be written in terms of superfields. As a byproduct, bootstrapping up to the full theory yields the first algorithmic approach for determining the SUSY Yang-Mills on-shell superspace action. This work paves the way toward discovering the effective theory for the collinear limit of ?=4 SUSY Yang-Mills.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:14867424006c6d2cd594795ee1eb621c27faaf1e5d@sns.ias.edu DTSTART:20170210T160000Z DTEND:20170210T173000Z SUMMARY:The Precision Frontier Seminar, "Searches for Light Pseudoscalars" (Ken Van Tilburg, Member, School of Natural Sciences, IAS; New York University) DESCRIPTION: LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148675230016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170210T184500Z DTEND:20170210T200000Z SUMMARY:High Energy Theory Seminar, "Loop Amplitudes from Ambitwistor Strings" (Yvonne Geyer, Member, School of Natural Sciences, IAS) DESCRIPTION:The last years have seen remarkable progress in understanding the scattering amplitudes of massless particles in arbitrary dimension. They exhibit structures and a simplicity completely obscured by the Feynman diagram approach, and can be shown to arise from worldsheet models with an auxiliary target space - ambitwistor space. After reviewing the key developments, I will discuss the worldsheet models and derive the loop integrands. Time permitting, I will focus on work in progress on deriving loop amplitudes from Riemann sphere correlators.

LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148701420016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170213T193000Z DTEND:20170213T210000Z SUMMARY:High Energy Theory Seminar, "Worldsheet String Theory in AdS/CFT and Lattice" (Valentina Forini, Humboldt-University Berlin) DESCRIPTION:String sigma-models relevant in AdS/CFT are highly non-trivial two-dimensional field theories for which predictions at finite coupling assume integrability and/or the duality itself. After having discussed general features of the perturbative approach, I will present progress on how to extract finite coupling information via the use of lattice field theory methods.

LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1487091600c0eb0c5583bc95fa859636a4e3306938@sns.ias.edu DTSTART:20170214T170000Z DTEND:20170214T183000Z SUMMARY:High Energy Physics Seminar, "Searches for New Physics at CMS and Precision Timing Detectors" (Cristián Peña) DESCRIPTION:Searches for dark matter and supersymmetry are part of an ambitious and well motivated quest to discover new physics at the LHC. In the first part of this seminar I will be presenting two novel searches for new physics using the data collected by the CMS experiment. The first is a search for dark matter in multijet events using the razor variables to discriminate signal from background events. The second is a search for anomalous production of Higgs bosons in association with jets, where the Higgs is reconstructed through its diphoton decay channel. The second part of my seminar will cover cutting edge detector R&D towards a device with ~10 ps time resolution. Such detectors will have a positively disruptive impact in future experiments such as the High Luminosity upgrade of the LHC by maintaining the current event reconstruction performance, which is expected to otherwise significantly deteriorate due to the high pileup environment.

LOCATION:Jadwin Hall, Room 111 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148710600007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20170214T210000Z DTEND:20170214T223000Z SUMMARY:Pheno & Vino Seminar, "The Astrophysics of Fuzzy Dark Matter" (Scott Tremaine, Institute for Advanced Study) DESCRIPTION:Few, if any, of the predictions of the standard Lambda CDM cosmological models have been successful on galaxy-sized scales. This lack of success is usually explained by the difficulty of modeling baryonic physics (star formation, supernova and black-hole feedback, etc.). An intriguing alternative is that the dark matter is an extremely light boson having a de Broglie wavelength of order a kiloparsec, often called fuzzy dark matter (FDM). I will describe some of the astrophysical phenomena associated with FDM, including a lower limit to the mass of dark halos, the presence of dense Bose-Einstein condensates in the centers of massive halos, evaporation of sub-halos by tunneling, relaxation due to interference patterns in dark-matter halos, growth of supermassive black holes by swallowing dark matter, etc. There is tension with observations of the Lyman-alpha forest, which favor somewhat greater particle masses than those needed for FDM to have a significant impact on galactic structure.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1487184300ddcbf452bffff0a1f9a416202b44514a@sns.ias.edu DTSTART:20170215T184500Z DTEND:20170215T200000Z SUMMARY:Physics Group Meeting, "Discussion of MOND and LCDM" (Matias Zaldarriaga, Faculty, School of Natural Sciences, IAS) DESCRIPTION:I will review the phenomenological successes of MOND on the scale of galaxies. I will discuss its failure on cosmological scales. These large scale problems have been understood for decades, are very robust and their origin can be easily understood. On the scales of galaxies, rotation curves are well described by the MOND force law without any need of dark matter. In the context of dark matter models this fact would seem to imply that the dark matter has to adjust itself to what the baryons are doing. I will review how this apparent miracle comes about in the galaxy formation models.

LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1487278800c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20170216T210000Z DTEND:20170216T220000Z SUMMARY:Hamilton Colloquium Series, "Invitation to Random Tensors" (Razvan Gurau, Centre de Physique Théorique (CPHT), École Polytechnique, France) DESCRIPTION:Random matrices are ubiquitous in modern theoretical physics and provide insights on a wealth of phenomena, from the spectra of heavy nuclei to the theory of strong interactions or random two dimensional surfaces.

The backbone of all the analytical results in matrix models is their 1/N expansion (where N is the size of the matrix). Despite early attempts in the '90s, the generalization of this 1/N expansion to higher dimensional random tensor models has proven very challenging. This changed with the discovery of the 1/N expansion (originally for colored and subsequently for arbitrary invariant) tensor models in 2010. In this talk I will present a short introduction to the modern theory of random tensors and its connections to random higher dimensional geometry.

Combinatorial maps (generated in the Feynman expansion of matrix models) can be classified by a non negative integer, the genus. Edge colored graphs (generated in the Feynman expansion of tensor models) can similarly be classified by a non negative integer, the degree. In this talk I will present this classification and discuss the associated 1/N expansion of tensor models at all orders.

LOCATION:Jadwin Hall, Fourth Floor, PCTS Seminar Room 407 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:14877018009a5ca379b29821892830e83f95cc0786@sns.ias.edu DTSTART:20170221T183000Z DTEND:20170221T200000Z SUMMARY:Experimental Physics Seminar, "Next-generation Atomic Clocks" (G. Edward Marti, JILA) DESCRIPTION:The accuracy of atomic clocks has improved a thousandfold over the last 15 years, driven by improvements in ultrastable lasers, quantum control, and our understanding of atomic interactions. The latest generation of optical lattice clocks are accurate enough to measure general relativity's gravitational redshift at the centimeter scale, to test physics beyond the Standard Model, and to reveal new emergent properties of quantum materials. In this talk, I will discuss the principles behind state-of-the-art optical lattice clocks and describe a clock that reaches a record accuracy of 1 mHz on an optical transition at 429 THz, a fractional frequency accuracy of 2 parts in 10^18. I will also discuss a next-generation clock that probes degenerate fermions in a three-dimensional optical lattice. By controlling atomic interactions and light shifts, this apparatus achieved a record atom-light coherence time of six seconds, reaching sub-100 mHz spectroscopic features. Finally, if time allows, I will discuss prospects for improved accuracy in a cryogenic strontium clock and for tests of fundamental physics with clocks.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148770720011d4ef4cc39a56ca0c663e848a839d9f@sns.ias.edu DTSTART:20170221T200000Z DTEND:20170221T213000Z SUMMARY:PCTS Presents the Director’s Lecturer, "Time Symmetric Formulation of Quantum Theory" (Yakir Aharonov, Chapman University and Professor Emeritus, Tel Aviv University, Israel) DESCRIPTION: LOCATION:Jadwin Hall, PCTS Seminar Room 407 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148771080007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20170221T210000Z DTEND:20170221T223000Z SUMMARY:Pheno & Vino Seminar, "Multidimensional Phase Space Methods for Mass Measurements and Decay Topology Determination" (Matthew Klimek, University of Texas) DESCRIPTION:The lack of conclusive evidence for new physics so far at the LHC suggests that future discoveries may manifest themselves with small numbers of signal events. In this case, it will be crucial to use analysis techniques that extract as much information as possible from a limited number of events. Collider events with multi-stage cascade decays fill out the kinematically allowed region in phase space with a density that is enhanced at the boundary. The boundary encodes all available information as regards the spectrum and is well populated even with moderate signal statistics due to this enhancement.

I will discuss the improvement in the precision of mass measurements for cascade decays with one invisible particle that is possible when the full boundary information is used, as well as the possibility of determining decay topologies with this information.

I discuss in my talk a reformulation of quantum mechanics in which each quantum system at any time is described by two Hilbert space vectors rather than one. One of the vectors propagates from a past boundary condition towards the present and the other propagates back to the present from a future boundary condition. I will show that this reformulation uncovers a host of fascinating new phenomena, some of which will be described in detail within this talk. Finally, I will show that this new reformulation suggests a novel solution to the notorious problem of the Quantum Measurement.

LOCATION:Jadwin Hall, Room A-10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148796190016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170224T184500Z DTEND:20170224T203000Z SUMMARY:High Energy Theory Seminar, "The Second Law of Quantum Complexity" (Leonard Susskind, Stanford University) DESCRIPTION: LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148822380016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170227T193000Z DTEND:20170227T210000Z SUMMARY:High Energy Theory Seminar, "Nonlinear Gravity from Entanglement" (Mark van Raamsdonk, University of British Columbia) DESCRIPTION: LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:14882976006c6d2cd594795ee1eb621c27faaf1e5d@sns.ias.edu DTSTART:20170228T160000Z DTEND:20170228T173000Z SUMMARY:The Precision Frontier Seminar, "Searches for Pseudoscalar Dark Matter Coupled to Photons" (Yoni Kahn, Princeton University) DESCRIPTION: LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148831560007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20170228T210000Z DTEND:20170228T223000Z SUMMARY:Pheno & Vino Seminar, "Ultralight Repulsive Dark Matter" (JiJi Fan, Brown University) DESCRIPTION:Ultralight scalar dark matter with mass at or below the eV scale and above 10^{-22} eV and pressure from repulsive self-interaction could form a Bose-Einstein condensate in the early Universe and maybe in galaxies as well. It has been suggested before that this scenario may provide a possible solution to the cusp/core problem and some specific model may even explain MOND phenomenology. I will discuss some challenges facing this scenario from the particle physics model building point of view.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148837680080b4a3b21023371fcdba6a1dc606f5a8@sns.ias.edu DTSTART:20170301T140000Z DTEND:20170301T230000Z SUMMARY:Simons Collaboration Workshop, "Simons Collaboration Workshop on Numerical Bootstrap" DESCRIPTION:

10:00 Andy Stergiou - "Mixed correlator 4D N=1 superconformal bootstrap"

11:15 Simon Caron-Huot - "Analyticity in spin and an inverse operator product expansion"

14:00 Denis Karateev - "Bootstrap Equations of Arbitrary Spin Representations in 4D CFTs"

LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148846320080b4a3b21023371fcdba6a1dc606f5a8@sns.ias.edu DTSTART:20170302T140000Z DTEND:20170302T230000Z SUMMARY:Simons Collaboration Workshop, "Simons Collaboration Workshop on Numerical Bootstrap" DESCRIPTION:

10:00 Shai Chester - "Monopole operators in U(1) Chern-Simons theories"

11:15 Madalena Lemos - "The 4d N=3 bootstrap and 2d long blocks"

14:00 Xi Yin - "Bootstrapping the spectral function"

15:15 Alessandro Vichi - "Update on the four current bootstrap"

LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1488488400c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20170302T210000Z DTEND:20170302T220000Z SUMMARY:Hamilton Colloquium Series, "Neutrino Physics from the Polarized Microwave Background" (Jo Dunkley, Princeton University) DESCRIPTION:Measurements of the Cosmic Microwave Background radiation have taught us a great deal about the origins and content of the universe, but there is still more information to be extracted. In the next decade we anticipate using new polarized microwave background data, and other cosmological data, to measure both the total mass of the neutrino particles, and the number of neutrino or other relativistic species. I will discuss our path to making this indirect detection of the absolute neutrino mass scale using the gravitational lensing of the microwave background and the clustering of galaxies, which will complement direct measurements. This will progress from data taken with the Planck satellite and the Atacama Cosmology Telescope Polarimeter in Chile, moving to new measurements made from the ground with the Simons Observatory and the CMB-S4 experiment, and from space with the PIXIE satellite.

LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148854960080b4a3b21023371fcdba6a1dc606f5a8@sns.ias.edu DTSTART:20170303T140000Z DTEND:20170303T230000Z SUMMARY:Simons Collaboration Workshop, "Simons Collaboration Workshop on Numerical Bootstrap" DESCRIPTION:

10:00 Fernando Alday - "Large spin perturbation theory"

11:15 Agnese Bissi - "Loops in AdS from CFT"

14:00 Petr Kravchuk - "Representation-theoretic approach to tensor structures and the Casimir equation"

LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1488808800f1fc8bec244de970cef379297b0ab55f@sns.ias.edu DTSTART:20170306T140000Z DTEND:20170306T220000Z SUMMARY:PCTS Workshop - CFT, "New Developments in Conformal Field Theory Above Two Dimensions" DESCRIPTION:This workshop will be held in conjunction with “The Quantum Hall Effect: Past, Present & Future (QHE)” workshop, held from March 8-10, 2017; Room 407 Jadwin Hall, PCTS.

While much has been known about CFTs in two space-time dimensions for a long time, the study of CFTs in more than two space-time dimensions has recently been undergoing significant progress. This workshop will include extensive studies of CFTs in three and higher dimensions, covering a variety of techniques such as the 1/N expansion, the epsilon expansion and the conformal bootstrap. CFT models have applications in condensed matter and statistical systems, but they are also very interesting for theoretical reasons, such as their relation to quantum gravity via the AdS/CFT correspondence.

LOCATION:Jadwin Hall, Fourth Floor, Room 407, PCTS Seminar Room COMMENT:FREE, but REQUIRED REGISTRATION is limited and available online URL:http://pcts.princeton.edu/pcts END:VEVENT BEGIN:VEVENT UID:1488895200f1fc8bec244de970cef379297b0ab55f@sns.ias.edu DTSTART:20170307T140000Z DTEND:20170307T220000Z SUMMARY:PCTS Workshop - CFT, "New Developments in Conformal Field Theory Above Two Dimensions" DESCRIPTION:This workshop will be held in conjunction with “The Quantum Hall Effect: Past, Present & Future (QHE)” workshop, held from March 8-10, 2017; Room 407 Jadwin Hall, PCTS.

While much has been known about CFTs in two space-time dimensions for a long time, the study of CFTs in more than two space-time dimensions has recently been undergoing significant progress. This workshop will include extensive studies of CFTs in three and higher dimensions, covering a variety of techniques such as the 1/N expansion, the epsilon expansion and the conformal bootstrap. CFT models have applications in condensed matter and statistical systems, but they are also very interesting for theoretical reasons, such as their relation to quantum gravity via the AdS/CFT correspondence.

LOCATION:Jadwin Hall, Fourth Floor, Room 407, PCTS Seminar Room COMMENT:FREE, but REQUIRED REGISTRATION is limited and available online URL:http://pcts.princeton.edu/pcts END:VEVENT BEGIN:VEVENT UID:1488913200c0eb0c5583bc95fa859636a4e3306938@sns.ias.edu DTSTART:20170307T190000Z DTEND:20170307T203000Z SUMMARY:High Energy Physics Seminar, "Search for Supersymmetry with Tau Leptons" (Alexis Kalogeropoulos, DESY) DESCRIPTION:Supersymmetry (SUSY) is a well-motivated theory beyond the standard model (SM)which provides solutions to several open questions in particle physics, e.g. the cancellation of quadratically divergent loop corrections to the mass of the Higgs boson.

In R-Parity conserving SUSY, the lightest SUSY particle (LSP) is stable and can be a viable dark matter candidate.

The cosmological model based on cold dark matter (CDM) and dark energy has been hugely successful in describing the observed evolution and large scale structure of our Universe. However, at small scales (in the smallest galaxies and at the centers of larger galaxies), a number of observations seem to conflict with the predictions CDM cosmology, leading to recent interest in alternative dark matter models. I will summarize a number of ways that baryonic physics can resolve the conflict between theory and observations, by significantly altering the structure and evolution of galaxies. Baryonic physics can create dark matter cores in galaxies, can form bulgeless disk galaxies, and alters the distribution and mass of satellite galaxies. I will also show that a proper consideration can reconcile theory with the observed velocity function of galaxies. Despite all of the successes of baryonic physics in reconciling CDM with observations, I will explain why alternative dark matter models are still viable and interesting.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1488981600f1fc8bec244de970cef379297b0ab55f@sns.ias.edu DTSTART:20170308T140000Z DTEND:20170308T220000Z SUMMARY:PCTS Workshop - CFT, "New Developments in Conformal Field Theory Above Two Dimensions" DESCRIPTION:This workshop will be held in conjunction with “The Quantum Hall Effect: Past, Present & Future (QHE)” workshop, held from March 8-10, 2017; Room 407 Jadwin Hall, PCTS.

While much has been known about CFTs in two space-time dimensions for a long time, the study of CFTs in more than two space-time dimensions has recently been undergoing significant progress. This workshop will include extensive studies of CFTs in three and higher dimensions, covering a variety of techniques such as the 1/N expansion, the epsilon expansion and the conformal bootstrap. CFT models have applications in condensed matter and statistical systems, but they are also very interesting for theoretical reasons, such as their relation to quantum gravity via the AdS/CFT correspondence.

LOCATION:Jadwin Hall, Fourth Floor, Room 407, PCTS Seminar Room COMMENT:FREE, but REQUIRED REGISTRATION is limited and available online URL:http://pcts.princeton.edu/pcts END:VEVENT BEGIN:VEVENT UID:14889816008376ef9c148cd2b20372a3cf786d4baa@sns.ias.edu DTSTART:20170308T140000Z DTEND:20170308T220000Z SUMMARY:PCTS Workshop - Quantum Hall Effect, "The Quantum Hall Effect: Past, Present and Future" DESCRIPTION:This workshop will be held in conjunction with the “New Developments in Conformal Field Theory Above Two Dimensions” workshop, held from March 6-8, 2017; Room 407 Jadwin Hall, PCTS.

The quantum Hall effect remains the cornerstone of our understanding of topological physics. One of the reasons for its continued relevance is consistent experimental progress, including new materials (e.g., graphene and zinc oxide) and even new platforms (optical cavities and photonic devices). It is also experiencing a theoretical revival due to a new understanding of the half-filled Landau level, and to intense interest in the interplay between quantum Hall states and geometry. This workshop will focus on recent advances in quantum Hall physics, with the aim to bring together different experimental and theoretical communities.

LOCATION:Jadwin Hall, Fourth Floor, Room 407, PCTS Seminar Room COMMENT:FREE, but REQUIRED REGISTRATION is limited and available online URL:http://pcts.princeton.edu/pcts END:VEVENT BEGIN:VEVENT UID:14890680008376ef9c148cd2b20372a3cf786d4baa@sns.ias.edu DTSTART:20170309T140000Z DTEND:20170309T220000Z SUMMARY:PCTS Workshop - Quantum Hall Effect, "The Quantum Hall Effect: Past, Present and Future" DESCRIPTION:This workshop will be held in conjunction with the “New Developments in Conformal Field Theory Above Two Dimensions” workshop, held from March 6-8, 2017; Room 407 Jadwin Hall, PCTS.

The quantum Hall effect remains the cornerstone of our understanding of topological physics. One of the reasons for its continued relevance is consistent experimental progress, including new materials (e.g., graphene and zinc oxide) and even new platforms (optical cavities and photonic devices). It is also experiencing a theoretical revival due to a new understanding of the half-filled Landau level, and to intense interest in the interplay between quantum Hall states and geometry. This workshop will focus on recent advances in quantum Hall physics, with the aim to bring together different experimental and theoretical communities.

LOCATION:Jadwin Hall, Fourth Floor, Room 407, PCTS Seminar Room COMMENT:FREE, but REQUIRED REGISTRATION is limited and available online URL:http://pcts.princeton.edu/pcts END:VEVENT BEGIN:VEVENT UID:1489093200c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20170309T210000Z DTEND:20170309T220000Z SUMMARY:Hamilton Colloquium Series, "Building Quantum Matter from Light: from Topological Photonics to Polariton Blockade" (Jonathan Simon, University of Chicago) DESCRIPTION:I will present our recent work building matter from light, beginning with a realization of Landau levels for optical photons in a non-planar (twisted) optical resonator and studying the impact of placing these photons in curved space. I will then discuss our recent success in mediating strong interactions between intra-cavity photons using Rydberg electromagnetically induced transparency. Combining these ideas will enable us to explore strongly correlated topological matter made of light. Time permitting, I will describe a parallel effort to build correlated matter from microwave photons, where circuit QED tools developed for quantum computing are harnessed to mediate interactions between photons. In this work, we are developing tools to stabilize incompressible matter by harnessing engineered dissipation. In summation, we explore photonic materials as a unique alternative to ultracold atoms in optical lattices and electrons in ionic lattices for exploring topological or quantum condensed matter.

LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:14891544008376ef9c148cd2b20372a3cf786d4baa@sns.ias.edu DTSTART:20170310T140000Z DTEND:20170310T220000Z SUMMARY:PCTS Workshop - Quantum Hall Effect, "The Quantum Hall Effect: Past, Present and Future" DESCRIPTION:This workshop will be held in conjunction with the New Developments in Conformal Field Theory Above Two Dimensions workshop, held from March 6-8, 2017; Room 407 Jadwin Hall, PCTS.The quantum Hall effect remains the cornerstone of our understanding of topological physics. One of the reasons for its continued relevance is consistent experimental progress, including new materials (e.g., graphene and zinc oxide) and even new platforms (optical cavities and photonic devices). It is also experiencing a theoretical revival due to a new understanding of the half-filled Landau level, and to intense interest in the interplay between quantum Hall states and geometry. This workshop will focus on recent advances in quantum Hall physics, with the aim to bring together different experimental and theoretical communities.

LOCATION:Jadwin Hall, Fourth Floor, Room 407, PCTS Seminar Room COMMENT:FREE, but REQUIRED REGISTRATION is limited and available online URL:http://pcts.princeton.edu/pcts END:VEVENT BEGIN:VEVENT UID:148917150016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170310T184500Z DTEND:20170310T200000Z SUMMARY:High Energy Theory Seminar, "SL(N) Chern-Simons, Cluster Algebras and Defects" (Mauricio Romo, Member, School of Natural Sciences, IAS) DESCRIPTION:I'll describe the cluster partition function (CPF), a computational tool that uses elements from cluster algebra and representation theory to describe the partition function of Chern-Simons theory with gauge group SL(N,C), on knot complements. I'll comment on its multiple applications to defects in the 3d-3d correspondence and, if time allows, about recent progress on perturbative invariants.

LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148942980016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170313T183000Z DTEND:20170313T200000Z SUMMARY:High Energy Theory Seminar, "$T\overline T$ and LST" (David Kutasov, University of Chicago) DESCRIPTION:

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1489599900ddcbf452bffff0a1f9a416202b44514a@sns.ias.edu DTSTART:20170315T174500Z DTEND:20170315T190000Z SUMMARY:Physics Group Meeting, "Kinematic Space and Applications" (Bartek Czech, Member, School of Natural Sciences, IAS; Stanford University) DESCRIPTION:

I will discuss kinematic space--the space of pairs of points in a CFT. Basic objects living in kinematic space are OPE blocks--contributions to the OPE from a single conformal family. In holographic theories, OPE blocks are dual at leading order in 1/N to integrals of effective bulk fields along geodesics or homogeneous minimal surfaces in AdS. To illustrate the usefulness of the kinematic language, I will sketch new, conceptually clean derivations of the following known results: (1) the form of the vacuum modular Hamiltonian, (2) the first law of entanglement in holography, (3) linearized Einstein's equations, (4) the HKLL form of local bulk operators, (5) geodesic Witten diagrams. If time permits, I will discuss some aspects of OPE blocks related to shadow representations of conformal symmetry.

LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:14896854006c6d2cd594795ee1eb621c27faaf1e5d@sns.ias.edu DTSTART:20170316T173000Z DTEND:20170316T190000Z SUMMARY:The Precision Frontier Seminar, "Light Vector Dark Matter: Inflationary Production & Laboratory Detection" (David Pinner, Princeton University) DESCRIPTION: LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148977270016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170317T174500Z DTEND:20170317T190000Z SUMMARY:High Energy Theory Seminar, "BPS Graphs for Class S" (Maxime Gabella, Member, School of Natural Sciences, IAS) DESCRIPTION:I will present the concept of a “BPS graph” (a special kind of spectral network) and illustrate its usefulness in the study of theories of class S. BPS graphs encode BPS quivers, even for higher rank and in the presence of non-full punctures, and lead to new constructions of BPS monodromies.

LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:148977360002f1b40565bc473810bbdad8ef595389@sns.ias.edu DTSTART:20170317T180000Z DTEND:20170317T190000Z SUMMARY:Particle Astrophysics Seminar, "Direct Detection of Dark Matter with Liquid Argon" (Quentin Riffard, Paris Diderot University, Paris) DESCRIPTION:A large number of astrophysical and cosmological observations at different scales supports the existence of a cold dark matter component in the Universe. At the Universe scale, this component is uniformly distributed and represents roughly 26% of the total mass-energy density of the Universe. The Weakly Interacting Massive Particle (WIMP), a generic particle, is one of the leading dark matter particle candidates: a massive particle interacting only through weak and gravitational interactions. This candidate is supported by the so-called "WIMP miracle" and could also be supported in particle physics by supersymmetric models. At the Milky Way scale, dark matter forms a static halo surrounding our galaxy. The relative motion of the solar system through the dark halo produces a flux of WIMP on Earth.

Through the weak interaction, WIMP could interact with ordinary matter producing nuclear recoils (NR) by elastic scattering. In the last two decades, a large experimental effort has been deployed by international collaborations in order to probe a direct detection of NR from WIMP-nucleus interactions. In this experimental context, multi-tone noble liquid TPC are good candidate for the dark matter searches. The DarkSide program is a step approach program aiming to build a large TPC filled with liquid argon (LAr). The first part of this presentation focuses on the potential of LAr as a target for dark matter searches, on the latest results from the DS-50 detector and the perspectives of the DarkSide program: the DS-20k detector.

For a complete understanding of LAr data, the characterization of several parameters is fundamental such as the scintillation efficiency for NR and the pulse-shape parameter for the NR/ER discrimination is fundamental. In order to improve the knowledge on these parameters, the ARIS collaboration built a small LAr double-phase TPC. A first data taking with mono chromatic neutrons was performed in Orsay (France) in October 2016. The second part of this presentation presents a status of the ARIS data analysis and a discussion of the strategy to extract the parameters.

I formulate the conformal crossing equation in a way that manifests the conformal representation theory. In this form the crossing equation can be generalized to any group. Using SU(2) as a toy model I compute solutions to the crossing equation in terms of the 6j-symbol of the group.

LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:149063940016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170327T183000Z DTEND:20170327T200000Z SUMMARY:High Energy Theory Seminar, "RG Flows Across Dimensions and Holography" (Nikolay Bobev, KU Leuven) DESCRIPTION:Superconformal field theories placed in nontrivial background fields for the metric and the continuous global symmetries exhibit a rich web of RG flows across dimensions. I will discuss several examples of such flows and emphasize some of their universal features. In addition, I will employ non-perturbative tools such as 't Hooft anomaly matching, a-, F-, and c-extremization, and holography to gain a quantitative understanding of some aspects of these theories. Finally, I will discuss the relevance of these results for a microscopic understanding of the entropy of supersymmetric black holes and strings in AdS.

LOCATION:Jadwin Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1490809500ddcbf452bffff0a1f9a416202b44514a@sns.ias.edu DTSTART:20170329T174500Z DTEND:20170329T190000Z SUMMARY:Physics Group Meeting, "Algebraic EE and Holography" (Jennifer Lin, Member, School of Natural Sciences, IAS) DESCRIPTION:In the first part of the talk, I’ll explore whether EE’s of subalgebras not organized by position space in a holographic CFT may be useful for bulk reconstruction. In particular I'll explain how the lengths of non-minimal geodesics in AdS3 conical defect backgrounds can be interpreted as the EE's of certain subalgebras in the dual CFT. This part will be based on 1608.02040. In the second part of the talk, I'll discuss how the Ryu-Takayanagi area seems to be a boundary entropy, that is the analog of an edge term one finds when defining EE in a gauge theory, and how one might try to test this.

LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:149098230016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170331T174500Z DTEND:20170331T190000Z SUMMARY:High Energy Theory Seminar, "Lightcone Cut Holography" (Netta Engelhardt, Princeton University) DESCRIPTION:In this talk, I will give an answer to the question “which QFT states holographically describe the emergence of semiclassical (conformal) geometry?” via a new construct in QFT: the causal density matrix. This new construct relies on the “lightcone cut” approach to spacetime emergence, and generalizes it to arbitrary QFTs (that may or may not have holographic duals). In the presence of a semiclassical spacetime, lightcone cuts explain both the emergence of holographic dimensions and the way in which geometry is encoded in a holographic dual. Properties of the causal density matrix indicate that some features of quantum error correction are more general than AdS/CFT. Within AdS/CFT, I will argue that the “reduced” causal density matrix is dual to the causal wedge.

LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:149124420016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170403T183000Z DTEND:20170403T200000Z SUMMARY:High Energy Theory Seminar, "Holographic Complexity: A Progress Report" (Rob Myers, Perimeter Institute) DESCRIPTION:I will describe some recent work studying proposals for computational complexity in holographic theories. I will discuss properties of the new gravitational observables and of complexity in the boundary theory.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:149132700021400aa74765d7335f39f88d5b26b50a@sns.ias.edu DTSTART:20170404T173000Z DTEND:20170404T183000Z SUMMARY:Precision Frontier Seminar, "Prospects for direct detection of the Cosmic Neutrino Background" (Matthew Low, Member, School of Natural Sciences, IAS) DESCRIPTION: LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:149133600007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20170404T200000Z DTEND:20170404T213000Z SUMMARY:Pheno & Vino Seminar, "Probing New Light Force Mediators: From Atomic Physics to LHCb" (Yotam Soreq, MIT) DESCRIPTION:In this seminar we explore the potential of probing new force carriers, which may be the portal to dark sectors, in the LHCb experiment and by precision isotope shift spectroscopy. We propose an inclusive search for dark photons at the LHCb experiment. For Run 3 of the LHC, we estimate that LHCb will have sensitivity to large regions of the unexplored dark-photon parameter space, especially in the 210–520 MeV and 10–40 GeV mass ranges.

In addition, we explore the potential of probing new light force-carriers, with spin-independent couplings to the electron and the neutron, using precision isotope shift spectroscopy. We show that the result of these measurement can be interpreted as bounds on new physics with minimal theory inputs. We apply the method to existing Ca+ data and project its sensitivity to possibly existing new bosons using narrow transitions in other atoms and ions. Provided no deviation from the standard model, future measurements could improve the current Ca+ bound by five orders of magnitude and even reach unprecedented sensitivity for bosons within the 10 keV to 10 MeV mass range.

Hadrons with heavy quarks play a special role in studies of structures created by strong interactions. The LHCb experiment, with the large production cross-sections, its hadron identification capabilities and triggers optimized to collect events with bottom and charm quarks, has reached a new level of sensitivity in detecting new, interesting states in baryon and meson sectors. Some of these states have been expected, like newly discovered five excitations of the doubly-strange and charmed baryon. Some of them are spectroscopic puzzles, like potential pentaquark states or, reported recently, four tetraquark candidates with hidden charm and strangeness. I will discuss the LHCb results on heavy hadrons and put them in a broader context of hadronic spectroscopy.

LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:149184900016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170410T183000Z DTEND:20170410T200000Z SUMMARY:High Energy Theory Seminar, "An Instability in Asymptotically AdS Black-Branes" (Umut Gürsoy, Utrecht University) DESCRIPTION:I will demonstrate presence of a vanishing momentum unstable quasi-normal mode in a certain class of asymptotically AdS black brane solutions and present the fully backreacted time evolution of the system resulting from this instability. I will discuss this instability in the context of the Gubser-Mitra conjecture that relates dynamical instabilities to thermal instabilities of the corresponding thermodynamic system. I will also discuss this in connection with violation of the recently conjectured conformal bound on the speed of sound in strongly interacting plasmas.

LOCATION:Jadwin Hall, PCTS Seminar Room COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:149193360007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20170411T180000Z DTEND:20170411T193000Z SUMMARY:Pheno & Vino Seminar DESCRIPTION:**NYU/Princeton/Stonybrook Joint Phenomenology Meeting (aka Pheno & Vino)**

10:40AM Welcome Neal Weiner (CCPP Seminar Room, 940)

10:45AM - 12:15 Student talks (10 min each) (CCPP Seminar Room, 940)

12:15-2:00 PM Lunch

2-3:15 Joint Seminar: Tim Tait (UC Irvine) * Evidence for a ~17 MeV Particle in Rare Beryllium-8 Decays?* (CCPP Seminar Room 940

3:30-4:30 Reception CCPP 9th Floor lobby area

Abstract: The ATOMKI group has recently reported a surprising result in experimental measurements of a rare transition of Beryllium-8 nuclei, which shows what appears to be an unexpected resonant structure in the invariant mass of e+e- produced when the 18.15 MeV excited state decays to the ground state, which they interpret as a new particle of mass around 17 MeV and with ultra-weak couplings to the Standard Model. I will review the experimental results, and discuss possible interpretations as a previously unappreciated nuclear physics or a manifestation of physics beyond the Standard Model, and give outlook for future sources of information which can hope to shed light on the situation.

LOCATION: COMMENT: URL:http://physics.as.nyu.edu/object/physics.directions END:VEVENT BEGIN:VEVENT UID:1492019100ddcbf452bffff0a1f9a416202b44514a@sns.ias.edu DTSTART:20170412T174500Z DTEND:20170412T190000Z SUMMARY:Physics Group Meeting, "Why the Energy Density is Positive" (Aron Wall, Member, School of Natural Sciences, IAS) DESCRIPTION:A physical system is stable if its Hamiltonian is bounded below, so that we can define a positive notion of "energy" relative to the ground state. But what about the local energy density - can that be negative? I will provide an elegant derivation that a positive energy density always exists, in (discrete or continuous) classical systems with one spatial dimension. When we try to apply the same argument to quantum systems, we will obtain a surprising result linking the energy to information theory.

LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1492113600c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20170413T200000Z DTEND:20170413T210000Z SUMMARY:Hamilton Colloquium Series, "Unusual Quasiparticle Correlation in Graphene" (Philip Kim, Harvard University) DESCRIPTION:

Interactions between particles in quantum many-body systems can lead to a collective behavior. In a condensed matter system consisting of weakly interacting particles, a propagating particle interacting with its surroundings can be viewed as a ‘dressed’ quasiparticle with renormalized mass and other dynamic properties. The lack of screening enables strong Coulomb interactions between charged particles, leading to new collective dynamics. In this talk, I will discuss three examples concerning strongly interacting quasiparticles in graphene. In the first example, it will be shown that the thermally populated electrons and holes to realize Dirac fluid, where a huge violation of Wiedemann-Franz law is observed. The second example is realizing magnetoexcitons to correlated quasiparticles in quantized Landau levels to form magnetoexcitons, which can condense into Bose-Einstein condensation. Finally, we will also discuss another way of correlated quasiparticles in graphene using superconducting proximity effect. Here, we employ the crossed Andreev reflection across thin Type II superconducting electrodes to correlated spatially separated quasiparticles. Under strong magnetic fields, the quantum Hall edge states can carry these quasiparticles.

LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:149219190016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170414T174500Z DTEND:20170414T190000Z SUMMARY:High Energy Theory Seminar, "The Conformal Bootstrap in the Regge Limit" (David Meltzer, Yale University) DESCRIPTION:The analytic bootstrap has revealed universal constraints and structures in higher dimensional CFTs which relate causality, positive energy conditions, and large spin subsectors of the theory. I will present recent work extending the study of the bootstrap equations to the Regge limit for large N CFTs. Using both the chaos bound and crossing symmetry, I will present new constraints on anomalous dimensions and OPE coefficients of double trace states and the couplings of operators to the leading Regge trajectory. Using AdS/CFT, these bounds come from requiring bulk causality and unitarity. Finally, I will show how solving the crossing equations in the Regge limit leads naturally to the construction of AdS exchange diagrams.

LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:149245380016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170417T183000Z DTEND:20170417T200000Z SUMMARY:High Energy Theory Seminar, "Six Point String Scattering: Simulation of Horizon Infallers" (Eva Silverstein, Stanford University) DESCRIPTION: LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1492545600615e3b586811f0fae382c76390977e8f@sns.ias.edu DTSTART:20170418T200000Z DTEND:20170418T210000Z SUMMARY:Pheno and Vino Seminar, "Surveying the Landscape of Axially-Coupled Dark Forces" (Siddharth Mishra-Sharma, Princeton University) DESCRIPTION:I will describe the landscape of constraints on MeV-GeV scale, hidden U(1) forces with nonzero axial-vector couplings to Standard Model fermions. While the purely vector-coupled dark photon, which may arise from kinetic mixing, is a well-motivated scenario, several MeV-scale anomalies motivate a theory with axial couplings which can be UV-completed consistent with Standard Model gauge invariance. I will present a representative renormalizable, UV-complete model of a dark photon with adjustable axial and vector couplings, discuss its general features, and show how some UV constraints may be relaxed in a model with nonrenormalizable Yukawa couplings at the expense of fine-tuning. I will survey the existing parameter space and projected reach of planned experiments, briefly commenting on the relevance of the allowed parameter space to low-energy anomalies in pi^0 and 8-Be* decay.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:149279670016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170421T174500Z DTEND:20170421T190000Z SUMMARY:High Energy Theory Seminar, "Continuous and Discrete Gauge Symmetries in F-Theory" (Mirjam Cvetic, University of Pennsylvania) DESCRIPTION:We present recent developments in F-theory compactifications and focus on advances in constructions of globally consistent F-theory compactifications with Abelian and discrete gauge symmetries, emphasizing technical advances and insights into higher-rank gauge symmetries. We also present recent studies of the origin of Abelian and discrete symmetries in Heterotic/F-theory duality. Furthermore, a new construction of Type IIB compactification with non-Abelian discrete gauge symmetry is highlighted.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:149305950016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170424T184500Z DTEND:20170424T200000Z SUMMARY:High Energy Theory Seminar, "Entanglement Entropy and the Colored Jones Polynomial" (Onkar Parrikar, University of Pennsylvania) DESCRIPTION:We will study the entanglement structure of states in Chern-Simons (CS) theory obtained by performing the Euclidean path-integral on certain highly non-trivial 3-manifolds, namely link complements in S^3. This will allow us to assign an entanglement entropy to any bi-partition of an n-component link into sub-links; these entropies in fact provide framing independent link-invariants. In U(1) CS theory, we will give a general formula for the entanglement entropy across a bi-partition of a generic n-link into sub-links. In the non-Abelian SU(2) theory, we study various interesting 2 & 3-links including the Whitehead link and Borromean rings, both of which have non-trivial entanglement structures. If time permits, we will consider SL(2,C) and mention connections with gravity and hyperbolic geometry.

LOCATION:Jadwin Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1493142300a0a055f79333dcef4a7a0c9ef9a70632@sns.ias.edu DTSTART:20170425T174500Z DTEND:20170425T190000Z SUMMARY:Informal High Energy Theory Seminar, "Integrability of d-dimensional Conformal Blocks" (Mikhail Isachenkov, Weizmann Institute of Science) DESCRIPTION: LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1493228700ddcbf452bffff0a1f9a416202b44514a@sns.ias.edu DTSTART:20170426T174500Z DTEND:20170426T190000Z SUMMARY:Physics Group Meeting, "On the Operator Content of dS" (Dionysios Anninos, Member, School of Natural Sciences, IAS) DESCRIPTION:We discuss the operator content of an asymptotic dS universe, using as an example the Vasiliev theory of massless interacting higher spin particles in a dS vacuum.LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1493323200c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20170427T200000Z DTEND:20170427T210000Z SUMMARY:Hamilton Colloquium Series, "LHC at 13 TeV" (James Olsen, Princeton University) DESCRIPTION:

In 2015 the Large Hadron Collider (LHC) resumed proton collisions at a new record energy of 13 trillion electronvolts (13 TeV) and doubled the interaction rate achieved in the 2010-2012 run. With the discovery of the Higgs boson in Run 1, the search for new particles and interactions beyond those described by the standard model has intensified in Run 2, during which the amount of data collected has already eclipsed the previous datasets at 7 and 8 TeV. I will describe the challenges presented by the new running conditions, how those challenges were met by the CMS experiment, and selected results from the 13 TeV data. Near-term and long-term goals will also be discussed, including detector upgrades targeting the High-Luminosity LHC era set to begin in the middle of the next decade.

LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:149340150016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170428T174500Z DTEND:20170428T190000Z SUMMARY:High Energy Theory Seminar, "4d/2d Correspondences, Localization and Surface Operators" (Wolfger Peelaers, Rutgers University) DESCRIPTION:Four-dimensional N=2 supersymmetric and superconformal quantum field theories take part in various 4d/2d correspondences, which map computations of certain protected data of the four-dimensional theory to problems in two-dimensional models. In this talk, I will explore the role of surface operators in two such correspondences, namely the AGT correspondence and the relation to chiral algebras. In the former, I will argue that a configuration of intersecting “M2-brane surface operators” in the four-dimensional theory translates in the insertion of a generic degenerate vertex operator, labeled by two arbitrary representations, in the Liouville/Toda correlator. In the correspondence with chiral algebras, considering the concrete example of free hypermultiplets, I will leverage a novel localization computation to identify the insertion of a class of surface operators orthogonal to the chiral algebra plane with the insertion of specific vertex operators in the chiral algebra.

LOCATION:Jadwin Hall, PCTS Seminar Room COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:14937498005424ec0f10f20d7c772d7007ae59f7da@sns.ias.edu DTSTART:20170502T183000Z DTEND:20170502T200000Z SUMMARY:PCTS Seventh Annual Lecturer, "Symmetry Protected Topological Insulators and Semimetals" (Charles Kane, University of Pennsylvania) DESCRIPTION:We will discuss recent developments in topological band theory, in which the combination of time reversal symmetry and crystal symmetries lead to novel insulating and semimetallic states. After introducing the interplay between symmetry and topology in the electronic structure of crystalline materials, we will discuss several examples of protected metallic states that can occur on the surface and in the bulk. These include Dirac semimetals in two and three dimensions, double Dirac semimetals and line node semimetals as well as new classes of topological crystalline insulators with surface states that violate symmetry enhanced doubling theorems. We will contrast semimetallic behavior that arises due to band inversion with filling enforced semimetals that arise due to the existence of non-symmorphic space group symmetries.

LOCATION:Jadwin Hall, PCTS, Room 407 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:149375520007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20170502T200000Z DTEND:20170502T213000Z SUMMARY:Pheno & Vino Seminar, "Relaxing the Composite Higgs Little Hierarchy" (Brian Batell, University of Pittsburgh) DESCRIPTION:I will describe a composite Higgs scenario in which a cosmological relaxation mechanism naturally gives rise to a hierarchy between the weak scale and the compositeness scale. This is achieved through the scanning of explicit global symmetry breaking couplings, and in turn the composite Higgs potential, by a relaxion field during a long period of inflation in the early universe. The mechanism is explored in detail in a specific composite Higgs model with QCD-like dynamics, and some potential experimental signatures of the scenario are highlighted.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1493833500ddcbf452bffff0a1f9a416202b44514a@sns.ias.edu DTSTART:20170503T174500Z DTEND:20170503T190000Z SUMMARY:Physics Group Meeting, "Thoughts on Inertia and Gravity from Entanglement in (A)dS-spacetimes" (Erik Verlinde, University of Amsterdam) DESCRIPTION: LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:14939424006949d8566d4b4de07b5f8ddafa58d54f@sns.ias.edu DTSTART:20170505T000000Z DTEND:20170505T013000Z SUMMARY:The Hamilton Lecture, "Topological Phases of Matter" (Charles Kane, University of Pennsylvania) DESCRIPTION:Matter can arrange itself in the most ingenious ways. In addition to the solid, liquid and gas phases that are familiar in classical physics, quantum mechanics enables the existence of electronic phases of matter that can have both exotic and useful properties. In the last century, the thorough understanding of the simplest quantum electronic phase - the electrical insulator - enabled the development of the solid state electronics technology that is ubiquitous in today's information age. In the present century, new "topological" electronic phases are being discovered that may enable future technologies by allowing the seemingly impossible to occur: indivisible objects, like an electron or a quantum bit of information, can be split into two, allowing mysterious features of quantum mechanics to be harnessed. Our understanding of topological phases, which was celebrated by the 2016 Nobel Prize in physics, builds on deep ideas in mathematics. We will try to convey that they are as beautiful as they are fundamental.

LOCATION:McDonnell, Room A02 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:14939964005424ec0f10f20d7c772d7007ae59f7da@sns.ias.edu DTSTART:20170505T150000Z DTEND:20170505T160000Z SUMMARY:PCTS Seventh Annual Lecturer, "Clustering in Luttinger Liquids and the Quantum Hall Effect" (Charles Kane, University of Pennsylvania) DESCRIPTION:The coupled wire model is a simple formulation of the fractional quantum Hall effect that provides an explicit connection between the bulk topological order and the edge conformal field theory in the context of a solvable electronic model of coupled Luttinger liquids. Here we will consider the effects of pairing and higher order clustering on the Luttinger liquids. We will argue that a single Luttinger liquid can exhibit a pairing transition that is related to the transition between a topological and trivial superconductor. Incoporating pairing in the coupled wire model allows a simple formulation of the Moore-Read state and it's cousins. We will go on to consider higher order clustering of k particles, which leads to a formulation of the Read-Rezayi $Z_k$ parafermion states and identify a class of "orbifold" quantum Hall states that generalize the $Z_4$ Read Rezayi state.

LOCATION:Jadwin Hall, PCTS, Room 407 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:149400630016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170505T174500Z DTEND:20170505T190000Z SUMMARY:High Energy Theory Seminar, "How Much Information Can We Get From Traversable Wormoles?" (Douglas Stanford, Member, School of Natural Sciences, IAS) DESCRIPTION:The traversable wormhole protocol of Gao, Jafferis and Wall gives us a glimpse behind the horizon of certain black holes. I will describe this effect and discuss some limited applications to the black hole information problem. Based on a recent paper with Maldacena and Yang.

LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:149426820016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170508T183000Z DTEND:20170508T200000Z SUMMARY:High Energy Theory Seminar, "Magnificent Four" (Nikita Nekrasov, Stony Brook University) DESCRIPTION:Supersymmetric gauge theories in various spacetime dimensions lead to enumerative problems: counting of holomorphic curves in Calabi-Yau manifolds, intersection theory on moduli spaces of instantons, limit shapes for random Young diagrams in two and three dimensions. The latter problem is related to dimer models and the models of crystal melting. We shall report on the recent developments in four dimensions, the ultimate dimension for crystal melting coming from supersymmetric gauge theory. The string theory context of the problem is the counting of bound states of D0 branes in the presence of the D8-antiD8 branes and a B-field. The random configurations are tilings of the 3-space by four types of squashed cubes. The similar problem of D0-D6 brane counting led to the partition function which was conjectured in 2004 to be given by the (square of the) Witten index of 11d supergravity. The conjecture was proven in 2015 by A.Okounkov. I will present the conjecture on the partition function of the new model. The M-theory interpretation of the problem remains a mystery.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1494438300ddcbf452bffff0a1f9a416202b44514a@sns.ias.edu DTSTART:20170510T174500Z DTEND:20170510T190000Z SUMMARY:Physics Group Meeting, "Link Invariants and Topological Quantum Matter" (Pavel Putrov, Member, School of Natural Sciences, IAS) DESCRIPTION:Gauging of bosonic and fermionic symmetry protected topological (SPT) states with discrete symmetry produces simple yet non-trivial topological quantum field theories (TQFTs). Some of the natural observables in such TQFTs are expectation values of line and surface operators linked in space-time. I would like to discuss what link invariants are produced by such observables, focusing mostly on dimensions 2+1 and 3+1 and using their path integral formulation.

LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1494505800dc77577fd8b3ac50dc27407d33fd4b0e@sns.ias.edu DTSTART:20170511T123000Z DTEND:20170511T210000Z SUMMARY:PCTS Spring Program, "Bangs, Bounces, Black Holes, and Bubbles: Where General Relativity Meets Cosmology" DESCRIPTION:**Workshop Organizers: **Anna Ijjas & Paul Steinhardt, PCTS**SPEAKERS**

Claudia de Rham, Imperial College

Rehan Deen, University of Pennsylvania

Will East, Perimeter Institute

Raphael Flauger, UCSD

David Garfinkle, Oakland University

Ruth Gregory, Durham University

Luis Lehner, Perimeter Institute

Jean-Luc Lehners, MPG

Hermann Nicolai, MPG

Burt Ovrut, University of Pennsylvania

Vasilis Paschalidis, Princeton University

Frans Pretorius, Princeton University

Rachel Rosen, Columbia University

Andrew Tolley, Imperial College

**Workshop Organizers: **Anna Ijjas & Paul Steinhardt, PCTS**SPEAKERS**

Claudia de Rham, Imperial College

Rehan Deen, University of Pennsylvania

Will East, Perimeter Institute

Raphael Flauger, UCSD

David Garfinkle, Oakland University

Ruth Gregory, Durham University

Luis Lehner, Perimeter Institute

Jean-Luc Lehners, MPG

Hermann Nicolai, MPG

Burt Ovrut, University of Pennsylvania

Vasilis Paschalidis, Princeton University

Frans Pretorius, Princeton University

Rachel Rosen, Columbia University

Andrew Tolley, Imperial College

The Schwarzian theory was proposed by A. Kitaev as a low energy effective theory for quantum mechanical systems presenting holographic behavior, beginning with the SYK model. In this talk we will study the Schwarzian theory as a limit of two dimensional Liouville theory. By using results of the conformal bootstrap of Liouville theory we will obtain the exact partition function and correlation functions of the Schwarzian theory. We will also discuss the out-of-time-ordered four-point function by using its monodromy from a 2d perspective.

LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1495043100ddcbf452bffff0a1f9a416202b44514a@sns.ias.edu DTSTART:20170517T174500Z DTEND:20170517T190000Z SUMMARY:Physics Group Meeting, "A few basics of deep learning" (Dima Krotov, Member, School of Natural Sciences, IAS) DESCRIPTION:I will give an elementary introduction to neural network models commonly used in deep learning. These include feed-forward neural networks, recurrent neural networks and memory models. If time permits, a few open problems in the field will also be discussed.LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:149547780016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170522T183000Z DTEND:20170522T200000Z SUMMARY:High Energy Theory Seminar, "Entanglement, Replicas and Thetas" (Sunil Mukhi, Tata Institute for Fundamental Research) DESCRIPTION: LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:149582070016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170526T174500Z DTEND:20170526T190000Z SUMMARY:High Energy Theory Seminar, "Black hole microstates in AdS4 and AdS5 from supersymmetric partition functions" (Kiril Hristov, Bulgarian Academy of Sciences, Sofia) DESCRIPTION:

This talk addresses the problem of counting the microstates of supersymmetric asymptotically AdS black holes in terms of a holographically dual field theory. We focus on a particular BPS class of AdS2 x S2 near-horizon geometry in N=2 gauged supergravity relevant both for AdS4 and AdS5 black holes. We consider in the large N limit the topologically twisted index of the ABJM theory and the Casimir energy of N=4 SYM and show that they correctly reproduce the Bekenstein-Hawking entropy of the AdS4 and AdS5 black holes, respectively. An extremization of the partition functions with respect to a set of chemical potentials is required. We interpret it as the selection of the exact R-symmetry of the superconformal quantum mechanics describing the horizon of the black holes.

LOCATION:Princeton Univ., PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:149789700016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170619T183000Z DTEND:20170619T200000Z SUMMARY:High Energy Theory Seminar, "Space of Field Theories, UV Completeness, and Integrability" (Alexander Zamolodchikov, Rutgers, The State University of New Jersey) DESCRIPTION: LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:150489270016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170908T174500Z DTEND:20170908T190000Z SUMMARY:High Energy Theory Seminar, "Asymptotic Symmetries in Effective Field Theories" (Prahar Mitra, Member, School of Natural Sciences, IAS) DESCRIPTION:A complete and universal equivalence between soft theorems inquantum field theories and asymptotic symmetries in flat spacetimes has recently emerged. We review these developments and show that the equivalence also extends to theories with higher derivative interactions.LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:150549750016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170915T174500Z DTEND:20170915T190000Z SUMMARY:High Energy Theory Seminar, "Weak Gravity Conjecture and Black Hole Thermodynamics" (Zachary Fisher, Perimeter Institute) DESCRIPTION:

The weak gravity conjecture (WGC) is a proposed bound on the mass of a charged particle in a consistent low-energy effective theory. We study quantum corrections to black hole entropy arising from a charged but WGC-violating scalar. In particular, we study the laws of black hole thermodynamics, and identify several surprising features which contradict the second and third laws in various regimes. This result is strong evidence that the WGC is necessary for a consistent theory.

LOCATION:Jadwin Hall, 4th Floor, PCTS Seminar Room COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1505746800e0bf42ce09252170a02e85927e59e785@sns.ias.edu DTSTART:20170918T150000Z DTEND:20170918T160000Z SUMMARY:Computer Science/Discrete Mathematics Seminar I, "Rigorous RG: A Provably Efficient and Possibly Practical Algorithm for Simulating 1D Quantum Systems" (Umesh Vazirani, University of California, Berkeley) DESCRIPTION:One of the great mysteries in computational condensed matter physics is the remarkable practical success of the Density Matrix Renormalization Group (DMRG) algorithm, since its invention a quarter century ago, for finding low energy states of 1D quantum systems (like the similarly successful simplex method for linear programming, DMRG takes exponential time in the worst case). From a computational complexity viewpoint, low energy states are simply near optimal solutions to (quantum) constraint satisfaction problems. Mathematically, the problem is specified by a succinctly described Hamiltonian - an exponentially large matrix, and the challenge is to find the eigenstates with small eigenvalues. Since the eigenstates live in an exponential dimensional space, it is a priori not even clear whether they can be succinctly described, let alone computed efficiently. In this talk I will describe novel combinatorial arguments showing that low energy states for systems of particles with nearest neighbor interactions in 1D can be described succinctly, leading to a provably efficient classical algorithm for computing them. A recent implementation of our algorithm shows promise for outperforming DMRG in hard cases with high ground space degeneracy or near criticality.

One of the cornerstones in physics is the Renormalization Group (RG) formalism, which provides a sweeping approach towards managing complexity in the quantum world. Our algorithm may be viewed as a rigorously justified RG-like procedure, and provides a new perspective on the subject.

The talk will be aimed at a broad audience of computer scientists and physicists, and I will not assume a background in quantum computing.

Based on joint work with Itai Arad, Zeph Landau and Thomas Vidick

LOCATION:Simonyi Hall Seminar Room COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1505754000131a37e1813498dd1cd8d84406433541@sns.ias.edu DTSTART:20170918T170000Z DTEND:20170918T180000Z SUMMARY:Condensed Matter Seminar, "Bounds on Transport" (Sean Hartnoll, Stanford University) DESCRIPTION:There is a long history to the idea that transport may be subject to fundamental constraints. I will argue that variants of these ideas offer promising ways to think about non-quasiparticle transport. I will discuss both proposed lower and upper bounds on transport, and I will suggest that such bounds may address long-standing transport puzzles in unconventional metals. I will discuss recent experimental probes of these ideas as well as theoretical connections to questions in quantum statistical mechanics.

LOCATION:Jadwin Hall, PCTS Seminar Room 407 COMMENT:Host: Professor Michael Zaletel URL: END:VEVENT BEGIN:VEVENT UID:150575940016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170918T183000Z DTEND:20170918T200000Z SUMMARY:High Energy Theory Seminar, "The Quantum Null Energy Condition from Causality" (Thomas Faulkner, University of Illinois at Urbana-Champaign) DESCRIPTION:I will present a general argument for the local bound on the null-null component of the stress tensor in a QFT called the Quantum Null Energy Condition. The argument involves the study of correlation functions of operators undergoing modular evolution associated to sub-regions of the QFT. Causality constrains this modular evolution which in AdS/CFT is related to the requirement of entanglement wedge nesting - a property fundamental to the study of subregion duality.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:150585300007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20170919T203000Z DTEND:20170919T213000Z SUMMARY:Pheno & Vino Seminar, "Perspectives on Astrophysical Searches for Dark Matter" (Stefano Profumo, University of California, Santa Cruz) DESCRIPTION:I will describe a few recent results and new directions in searching for the nature of dark matter as a particle with astronomical observations and with cosmic ray measurements.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:150610230016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170922T174500Z DTEND:20170922T190000Z SUMMARY:High Energy Theory Seminar, "Correlation Functions in N=4 SYM From Integrability" (Shota Komatsu, Member, School of Natural Sciences, IAS) DESCRIPTION:I will give an overview of the integrability-based approach to study correlation functions in planar N=4 SYM. The basic strategy is to "divide and conquer": We decompose the correlators of single-trace operators into fundamental objects called hexagon form factors, and compute each hexagon form factor by using integrability. I will firstdiscuss how the method works in three-point functions and then generalize it to higher-point functions. Time permitting, I will explain more recent developments and possible future directions.LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:150636420016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170925T183000Z DTEND:20170925T200000Z SUMMARY:High Energy Theory Seminar, "Conformal Field Theories and Three Point Functions" (Subham Dutta Chowdhury, Indian Institute of Science) DESCRIPTION:

Conformal invariance allows additional unique parity-odd tensor-structures for three-point functions involving the stress tensor, T, and a conserved U(1) current, j, in 2+1 dimensional conformal field theories that violate parity, apart from the usual parity even structures. Following the conformal collider physics setup of Hofman and Maldacena, we put constraints on the parity violating as well as parity preserving parameters of a general CFT in d=3. We find that large N Chern-Simons theories coupled to a fundamental fermion/boson saturate the bounds that we have derived. An application of the conformal collider bounds is observed in the form of sum rules which puts constraints on spectral densities of any CFT at finite temperature. We derive spectral sum rules in the shear channel for conformal field theories at finite temperature in general *d*≥3 dimensions. We show that the sum rule can be written in terms the parity even Hofman-Maldacena variables *t*2, *t*4 which determine the three point function of the stress tensor. We then use collider constraints and obtain bounds on the sum rule which are valid in any CFT.

Dark matter that interacts with the standard model (SM) through the “neutrino portal” is a possibility that is relatively less well studied than other scenarios. In such a setup, the dark matter communicates with the SM primarily through its interactions with neutrinos. In this talk, I will motivate neutrino portal dark matter and discuss some new tests of this possibility.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1506534300ddcbf452bffff0a1f9a416202b44514a@sns.ias.edu DTSTART:20170927T174500Z DTEND:20170927T184500Z SUMMARY:Physics Group Meeting, "Markovian Property of Vacuum State and the a-theorem" (Horacio Casini, Centro Atómico Bariloche) DESCRIPTION:The vacuum state reduced to a region of the space gives a density matrix which can be written in a thermal-like form. In this "thermal" density matrix the role of the Hamiltonian is played by the so called entanglement or modular Hamiltonian. Surprisingly, this modular Hamiltonian has a local universal expression in terms of the stress tensor for a large class of regions with boundary on a null plane. We will show that this property, together with strong subadditivity of entanglement entropy, gives place to an entropic version of the a-theorem about irreversibility of the renormalization group in d=4.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1506628800c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20170928T200000Z DTEND:20170928T213000Z SUMMARY:Hamilton Colloquium Series, "Higher-spin Gravity and Conformal Field Theory" (Simone Giombi, Princeton University) DESCRIPTION:Higher-spin gravity is a generalization of Einstein's general relativity, which involves towers of interacting massless fields of arbitrarily high spin. It has an infinite dimensional higher-spin gauge symmetry, and can be consistently constructed in the presence of a non-zero cosmological constant. I will give an overview of higher-spin gravity theories, with a focus on their role in the context of the AdS/CFT correspondence, a remarkable "holographic" duality between quantum gravity in anti-de Sitter (AdS) space and conformal field theory (CFT) in one less dimension. Higher-spin theories provide dual gravitational descriptions of some classic field theoretical models, such as the Wilson-Fisher fixed point of the O(N) vector model, and the Gross-Neveu model. Generalizations of the higher-spin AdS/CFT correspondence, which involve the Chern-Simons gauge theory, have suggested new boson-fermion dualities in two spatial dimensions.

LOCATION:Jadwin Hall, Room A-10 COMMENT:Host: Igor Klebanov -- Tea at 3:30 pm, Loung Area outside of Jadwin Hall A-10 URL:http://phy.princeton.edu/events/donald-r-hamilton-colloquium-series END:VEVENT BEGIN:VEVENT UID:150670710016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20170929T174500Z DTEND:20170929T190000Z SUMMARY:High Energy Theory Seminar, "Transport in Chern-Simons-Matter Theories" (Raghu Mahajan, Princeton University) DESCRIPTION:The frequency-dependent longitudinal and Hall conductivities --- $\sigma_{xx}$ and $\sigma_{xy}$ --- are dimensionless functions of $\omega/T$ in 2+1 dimensional CFTs at nonzero temperature. These functions characterize the spectrum of charged excitations of the theory and are basic experimental observables. We compute these conductivities for large $N$ Chern-Simons theory with fermion matter. The computation is exact in the 't Hooft coupling $\lambda$ at $N = \infty$. We describe various physical features of the conductivity, including an explicit relation between the weight of the delta function at $\omega = 0$ in $\sigma_{xx}$ and the existence of infinitely many higher spin conserved currents in the theory. We also compute the conductivities perturbatively in Chern-Simons theory with scalar matter and show that the resulting functions of $\omega/T$ agree with the strong coupling fermionic result. This provides a new test of the conjectured 3d bosonization duality. In matching the Hall conductivities we resolve an outstanding puzzle by carefully treating an extra anomaly that arises in the regularization scheme used.

LOCATION:Jadwin Hall, 4th Floor, PCTS Seminar Room COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:150696900016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20171002T183000Z DTEND:20171002T200000Z SUMMARY:High Energy Theory Seminar, "Twofold Symmetries and Simplification of the Gravity Action" (Grant Remmen, University of California, Berkeley) DESCRIPTION:While the canonical formulation of graviton perturbation theory is calculationally complex, the freedoms of nonlinear field redefinition and gauge fixing allow for immense simplification and the uncovering of new structures in perturbative gravity. In particular, we recast the Einstein-Hilbert action into a form that is invariant to all orders under a twofold Lorentz symmetry suggestive of the double copy between gauge theory and gravity. Furthermore, we derive field bases in which graviton perturbation theory is drastically simplified. We find a purely cubic formulation of perturbative gravity via the introduction of a single auxiliary field. With a different judicious choice of field redefinition and gauge fixing, we construct an especially compact form for the Einstein-Hilbert action in which all graviton interactions are simply proportional to the graviton kinetic term. All of our results can be extended to perturbation about curved background spacetimes.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:150706080007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20171003T200000Z DTEND:20171003T210000Z SUMMARY:Pheno & Vino Seminar, "Astrophysical Searches for Weakly-coupled Particles: From Black Holes to Red Giants" (Robert Lasenby, Perimeter Institute) DESCRIPTION:Astrophysical environments, with their extremes of size, density, and temperature, provide unique opportunities to probe new physics - in particular, to look for light, weakly-coupled particles beyond the Standard Model. I will talk about two such ways. The first is based on the phenomenon of black hole superradiance, through which ultra-light bosons can extract energy and momentum from spinning astrophysical black holes. This can cause spin-down of the black hole, and monochromatic gravitational wave signals from the resulting bosonic cloud, which could be detected at Advanced LIGO and future gravitational wave observatories.

I will also talk about the effects of new light particles on stellar energy transport. If such particles are produced in the hot cores of stars, then they can escape from the star and carry away energy, affecting its structure and evolution. I’ll describe how the plasma environment in stellar cores can parametrically alter the rates for these process, and how this can significantly change the constraints and discovery potential for some new particle candidates.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:15072255003b0d5a1f76089c7b521594f2dc128901@sns.ias.edu DTSTART:20171005T174500Z DTEND:20171005T190000Z SUMMARY:Special High Energy Theory Seminar, "Constraints on Particle Physics and Inflation from Quantum Gravity Conjectures" (Irene Valenzuela, Max-Planck-Institut für Physik) DESCRIPTION:Consistency with quantum gravity can have significant consequences on low energy physics. For instance, using the Weak Gravity Conjecture, it has been recently argued by Ooguri and Vafa that non supersymmetric stable AdS vacua are incompatible with quantum gravity. However, it is known that AdS vacua can appear from compactifying the Standard Model to 2 or 3 dimensions. By requiring the absence of these vacua we can put constraints on the SM and BSM spectra, obtaining a lower bound for the cosmological constant in terms of the neutrino masses. This can also be translated into an upper bound for the EW scale around the TeV range, bringing a new perspective into the issue of the EW hierarchy. Another example of a quantum gravity constraint refers to the size of the moduli space, constraining the scalar field range which is available before the effective theory breaks down due to the appearance of infinitely many exponentially light states. I will explain how this behaviour is also generic for axions in flux string compactifications once we take into account backreaction effects. This disfavours transplanckian excursions in string embeddings of the axion monodromy proposal used for Inflation or Cosmological Relaxation.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1507233600c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20171005T200000Z DTEND:20171005T210000Z SUMMARY:Hamilton Colloquium Series, "The Physics of Star Formation Feedback and Self-Regulation" (Eve Ostriker, Princeton University) DESCRIPTION:At all scales in the Universe, gravity wages a perpetual campaign to compress baryons to ever higher densities. Cosmic filaments, galaxies, interstellar clouds, and individual stars represent successive failures in the struggle against gravity. But at the bottom of the scale, stars fight back. Stellar nuclear burning creates energy, and “feedback” of this energy in various forms is essential to slowing and reversing gravitational collapse. The most important forms of stellar feedback are ultraviolet radiation and supernova blast waves. Both of these are produced by massive stars that have very short lives, and hence feedback is tightly coupled with star formation itself. The destructive effects of star formation feedback are widely seen even in popular astronomical images, but we have only recently developed the computational methods and theoretical framework that enable us to quantify and understand the physics involved. In this talk, I will describe recent modeling of three different forms of feedback at three different scales. At the smallest scale, I will show how stellar radiation from young clusters limits collapse and expels most of the gas in star-forming giant molecular clouds. At intermediate scales, I will explain how supernova blasts drive turbulence that maintains vertical equilibrium and controls star formation rates in the interstellar medium of disk galaxies like our own Milky Way. At large scales, I will argue that cosmic rays (which are accelerated by supernova shocks) may be able to propel gas out of dwarf galaxies at a higher rate than the remaining gas is locked up in stars, helping to explain why dwarfs are so baryon deficient. Each process represents a form of star formation self-regulation, and highlights different fascinating aspects of the physics of astrophysical fluids.

LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:150757380016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20171009T183000Z DTEND:20171009T200000Z SUMMARY:High Energy Theory Seminar, "Causality and the Length Operator" (Thomas Hartman, Cornell University) DESCRIPTION:Causality in quantum field theory is encoded in the averaged null energy condition. I will describe how, in large-N CFTs, this energy condition is replaced by a stronger inequality involving the spectrum of the length operator in the dual AdS. This relates unitarity in the CFT to the bulk causal structure, and gives a simple explanation for constraints on higher-curvature gravity. I will also discuss the information-theoretic interpretation, and implications for subregion duality.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:150764760044aac842e28e6d643ceb45c07479da83@sns.ias.edu DTSTART:20171010T150000Z DTEND:20171010T160000Z SUMMARY:Informal Physics Discussion, "Lorentz Covariant Theories with Causality Violation" (Harvey Reall, University of Cambridge) DESCRIPTION: LOCATION:Bloomberg Hall Astrophysics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:15076575003b0d5a1f76089c7b521594f2dc128901@sns.ias.edu DTSTART:20171010T174500Z DTEND:20171010T190000Z SUMMARY:Special High Energy Theory Seminar, "Indices, Localization, Rational Invariants, and H-Saddles" (Piljin Yi, Korean Institute for Advanced Study) DESCRIPTION:In recent years, varieties of index-like quantitites have been computed by exact path integral, a.k.a. the localization. For gauge theories, the computations reduces to contour integrals, famously riddled with subtleties. However, the interpretation of the results, which should be really called the twisted partition functions rather than the indices, seem to require even more

care.

After a cursory review of recent derivations and accompanying subtleties with empasis on 1d and 2d, we consider theories with noncompact Coulomb phases. Rational nature of the 1d twisted partition functions is observed and physically explained, which gives us an unexpcted tool for extracting the integral refined

index out of the twisted partition functions. Applied to pure Yang-Mills, this solves an old problem of counting D0 bound states in orbifolded M-theory, and, along the way, we resolve a critical conflict, circa 1999-2002, between Kac/Smilga and

Staudacher/Pestun by isolating the notion of H-saddles. The latter proves to be a universal feature of partition functions in the high "temperature" limit, in any spacetime dimensions, with serious ramifications on recent proposals on limits of 4d partition functions.

In certain models of a QCD axion, finite density corrections to the axion potential can result in the axion being sourced by large dense objects.

There are a variety of ways to test this phenomenon, but perhaps the most surprising effect is that the axion can mediate forces between neutron stars that can be as strong as gravity. These forces can be attractive or repulsive and their presence can be detected by Advanced LIGO observations of neutron star inspirals. By a numerical coincidence, axion forces between neutron stars with gravitational strength naturally have an associated length scale of tens of kilometers or longer, similar to that of a neutron star. Future observations of neutron star mergers in Advanced LIGO can probe many orders of magnitude of axion parameter space. Because the axion is only sourced by large dense objects, the axion force evades fifth force constraints. We also outline several other ways to probe this phenomenon using electromagnetic signals associated with compact objects.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1507743900ddcbf452bffff0a1f9a416202b44514a@sns.ias.edu DTSTART:20171011T174500Z DTEND:20171011T190000Z SUMMARY:Physics Group Meeting, "Delineating the Swampland via the Weak Gravity Conjecture" (Tom Rudelius, Member, School of Natural Sciences, IAS) DESCRIPTION:The set of low-energy effective theories that do not admit an ultraviolet completion in string theory is known as the ``swampland." Developing criteria to determine which effective theories belong in the string landscape and which ones belong in the swampland is a daunting task, but one of the most promising candidates is the Weak Gravity Conjecture (WGC). In this talk, we will see that the WGC, if true, has important consequences for axion inflation, and we will explore possible variants of the conjecture.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1507838400c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20171012T200000Z DTEND:20171012T210000Z SUMMARY:Hamilton Colloquium Series, "Protein Phase Transitions in and out of Cells" (Ned Wingreen, Princeton University) DESCRIPTION:Biologists have recently come to appreciate that eukaryotic cells are home to a multiplicity of non-membrane bound compartments, many of which form and dissolve as needed for the cell to function. These dynamical “liquid droplets” enable many central cellular functions – from ribosome assembly, to RNA regulation and storage, to signaling and metabolism. While it is clear that these compartments represent a type of separated phase, what controls their formation, how specific biological components are included or excluded, and how these structures influence physiological and biochemical processes remain largely mysterious. I will discuss recent experiments on phase separated droplets both in vitro and in vivo, and will present theoretical results that highlight a novel “magic number” effect relevant to the formation and control of two-component phase separated liquid droplets.

LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:150791670016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20171013T174500Z DTEND:20171013T190000Z SUMMARY:High Energy Theory Seminar, "Towards New Positive Energy Theorems in Quantum Field Theory" (Nima Lashkari, MIT) DESCRIPTION:I review the definition of the relative modular operators in quantum field theory from a heuristic and information-theoretic point of view. I work out a few examples in conformal field theories. I argue how and why thinking in terms of the relative modular operator in the recent years has led (and is likely to lead) to proving new generalized positive energy theorems in quantum field theory.

LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:150816240067105a97d263677a4d7a2c4e91f6b02e@sns.ias.edu DTSTART:20171016T140000Z DTEND:20171016T163000Z SUMMARY:LIGO Press Conference DESCRIPTION:As you may have heard, the LIGO collaboration is planning a major announcement on Monday, at 10 AM Eastern. The rumor is that they have found a pair of colliding neutron stars. We will have a viewing party of the press conference in the PCTS auditorium, starting at 10 AM sharp; please come if you are interested. The PCTS auditorium is on the 4th floor of Jadwin Hall; make a left out of the elevators or a right out of the stairs, and take it to the end.

LOCATION:Princeton Center for Theoretical Physics (PCTS), Jadwin Hall, 4th floor, Auditorium COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:150817860016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20171016T183000Z DTEND:20171016T200000Z SUMMARY:High Energy Theory Seminar, "Black Holes from Cosmic Inflation" (Alexander Vilenkin, Tufts University) DESCRIPTION:Spherical domain walls and vacuum bubbles can spontaneously nucleate and expand during the inflationary epoch in the early universe. After inflation ends, the walls and/or bubbles form black holes with a wide spectrum of masses. For some parameter values, the black holes can serve as dark matter or as seeds for supermassive black holes at galactic centers. This mechanism of black hole formation is very generic and has important implications for the global structure of the universe. Observation of black holes with the predicted mass spectrum would provide evidence for inflation and for the existence of a multiverse.

LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:150827040007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20171017T200000Z DTEND:20171017T210000Z SUMMARY:Pheno & Vino Seminar, "Gamma-ray Constraints on Decaying Dark Matter and Implications for IceCube" (Nick Rodd, MIT) DESCRIPTION:Utilising the Fermi measurement of the gamma-ray spectrum toward the inner Galaxy, I will explain how to derive some of the strongest constraints on dark matter lifetimes in the mass range from hundreds of MeV to above an EeV. The limits derived disfavour a decaying DM interpretation of the astrophysical neutrino flux observed by IceCube, and I will review why that possibility has received some attention in the literature recently.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1508443200c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20171019T200000Z DTEND:20171019T210000Z SUMMARY:Hamilton Colloquium Series, "Towards a Quantum Internet with Electron Spins" (Jason Petta, Princeton University) DESCRIPTION:Tremendous progress has been achieved in the coherent control of single quantum states (single charges, phonons, photons, and spins). At the frontier of quantum information science are efforts to hybridize different quantum degrees of freedom. For example, by coupling a single photon to a single electron fundamental light-matter interactions may be examined at the single particle level to reveal exotic quantum effects, such as single atom lasing. Coherent coupling of spin and light, which has been the subject of many theoretical proposals over the past 20 years, could enable a quantum internet where highly coherent electron spins are used for quantum computing and single photons enable long-range spin-spin interactions. In this colloquium I will describe experiments where we couple a single spin in silicon to a single microwave frequency photon. The coupling mechanism is based on spin-charge hybridization in the presence of a large magnetic field gradient. Spin-photon coupling rates *g*s/2p > 10 MHz are achieved and vacuum Rabi splitting is observed in the cavity transmission, indicating single spin-photon strong coupling. These results open a direct path toward entangling single spins at a distance using microwave frequency photons.

Goldstone modes arising from spontaneously broken symmetries can be added to a hydrodynamic description of charge transport to model quantum critical effects in metals from a symmetry point of view. I will discuss the setup and the effects of weak disorder and melting of the ordered state (giving rise to phase fluctuations) on the conductivity.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:150878340016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20171023T183000Z DTEND:20171023T200000Z SUMMARY:High Energy Theory Seminar, "Entropic A Theorem and the Markov Property of the Vacuum" (Eduardo Teste, Instituto Balseiro, Centro Atomico Bariloche) DESCRIPTION:A state is said to be Markovian if it fulfills the important condition of saturating the Strong Subadditivity inequality. I will show how the vacuum state of any relativistic QFT is a Markov state when reduced to certain geometric regions of spacetime. For the CFT vacuum, the Markov property is the key ingredient to prove the A theorem (irreversibility of the RG flow in relativistic QFT in d=4 spacetime dimensions) using vacuum entanglement entropy. This extends the entropic proofs of the c and F theorems in dimensions d=2 and d=3, giving a unified picture. I will also comment on the relation of this Markov property with the unitarity bound and holography.

LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:150887520016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20171024T200000Z DTEND:20171024T210000Z SUMMARY:High Energy Theory Seminar, "Bulk Locality from Subregion Duality" (Fabio Sanches, University of California, Berkeley) DESCRIPTION:I will explain a procedure to determine if a given nonlocal operator in a large-N holographic CFT is dual to a local bulk operator on the geometry associated with a particular code subspace of the CFT. This procedure does not presuppose knowledge of the bulk geometry. The process can pick out local operators in a large region of the bulk, called the “localizable region,” that can extend beyond event horizons in certain cases. The method relies heavily on the quantum error correcting structure of AdS/CFT and, in particular, on entanglement wedge reconstruction. As a byproduct of this machinery, I will show that we can reconstruct the metric in the localizable region up to a conformal factor. This suggests a connection between this program and the light-cone cut approach to bulk reconstruction.

LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1508953500ddcbf452bffff0a1f9a416202b44514a@sns.ias.edu DTSTART:20171025T174500Z DTEND:20171025T190000Z SUMMARY:Physics Group Meeting, "Boundary State Black Holes: Escapability and Reconstruction of the Interior" (Ahmed Almheiri, Member, School of Natural Sciences, IAS) DESCRIPTION:Boundary state black holes are single sided pure black holeswith an End-of-the-World Brane cutting off the spacetime in the interior. I demonstrate that certain Hamiltonian deformations tuned to the black hole microstate inject negative energy causing the horizon to recede, allowing for signals to escape the interior. Also, previous ideas describe how these states may be prepared by considering the Thermofield Double state dual to the eternal black hole and performing a complete measurement on one of the boundaries. I describe a naive tension between this and theidea that entanglement between the two boundaries is necessary for the existence of the interior. I show how positing that AdS/CFT implements a quantum error correcting code resolves this tension and maintains the existence of the interior geometry. Moreover, I describe how to prepare an (almost) entire basis of black hole microstates all of which have smooth interiors, and whose modes are mapped into the remaining boundary in a state dependent way.LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1509048000c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20171026T200000Z DTEND:20171026T210000Z SUMMARY:Hamilton Colloquium Series, "Quantum Mechanics and the Geometry of Spacetime" (Juan Maldacena, Institute for Advanced Study) DESCRIPTION:

Black holes are fascinating objects which pose interesting puzzles for quantum physics. Studying these puzzles we are led to quantum mechanical models that describe special black holes as seen from the outside. Extrapolating from these descriptions we conclude that entanglement can create geometric connections or wormholes. Moreover, quantum teleportation can be interpreted as traveling through the wormhole.

LOCATION:Jadwin Hall, Room A10 COMMENT:Host: Igor Klebanov -- Tea at 3:30 p.m., Professor’s Lounge, 2nd floor, Jadwin Hall URL: END:VEVENT BEGIN:VEVENT UID:150912630016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20171027T174500Z DTEND:20171027T190000Z SUMMARY:High Energy Theory Seminar, "A Hydrodynamical Theory for Quantum Many-body Chaos" (Hong Liu, MIT) DESCRIPTION: LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:150937560016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20171030T150000Z DTEND:20171030T160000Z SUMMARY:High Energy Theory Seminar, "Surprises of Quantization in de Sitter Space" (Emil Akhmedov, ITEP Moscow) DESCRIPTION:I will talk about loop infrared effects in de Sitter QFT. Namely about their types, physical meaning and origin and also about their resumation.

LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:150938820016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20171030T183000Z DTEND:20171030T200000Z SUMMARY:High Energy Theory Seminar, "What does the Revolution in Artificial Intelligence Mean for Physics?" (Kyle Cranmer, New York University) DESCRIPTION:There is no doubt that there is a revolution going on in machine learning and artificial intelligence, but what does it mean for physics? Is it all hype, or will it transform the way we think about and do physics?

I will describe machine learning from a physicist's perspective and isolate a few research areas that I think may be transformative. I will discuss how we can unpack physicist's healthy skepticism and trepidation about the use of machine learning and reformulate those concerns into quantitative or operational objectives. I will also advocate the development of hybrid machine learning techniques imbued with physics knowledge, which I call “physics-aware machine learning".

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1509453000848d6c35730ad0eb225a96e1943db197@sns.ias.edu DTSTART:20171031T123000Z DTEND:20171031T210000Z SUMMARY:PCTS Program, "20 Years Later: The Many Faces of AdS/CFT" DESCRIPTION:

**The first day of the conference, October 31, 2017, will be held in McDonnell Hall, Room A02.**

**On November 1, 2, 3, the conference will be held in Room 407 Jadwin Hall.**

Much of our current understanding of quantum gravity and of strongly coupled gauge theory comes from the AdS/CFT correspondence. This workshop celebrates the 20th anniversary of AdS/CFT. We will take stock of the past 20 years of progress in understanding the holographic dictionary, applications of the correspondence, implications for quantum gravity and strongly coupled field theories, as well as using lessons from AdS/CFT to understand holographic quantum gravity in a more general context.

LOCATION: COMMENT: URL:http://pcts.princeton.edu/pcts/20YearsAdSCFT/20Years2017.html END:VEVENT BEGIN:VEVENT UID:1509539400848d6c35730ad0eb225a96e1943db197@sns.ias.edu DTSTART:20171101T123000Z DTEND:20171101T210000Z SUMMARY:PCTS Program, "20 Years Later: The Many Faces of AdS/CFT" DESCRIPTION:

**The first day of the conference, October 31, 2017, will be held in McDonnell Hall, Room A02.**

**On November 1, 2, 3, the conference will be held in Room 407 Jadwin Hall.**

Much of our current understanding of quantum gravity and of strongly coupled gauge theory comes from the AdS/CFT correspondence. This workshop celebrates the 20th anniversary of AdS/CFT. We will take stock of the past 20 years of progress in understanding the holographic dictionary, applications of the correspondence, implications for quantum gravity and strongly coupled field theories, as well as using lessons from AdS/CFT to understand holographic quantum gravity in a more general context.

LOCATION: COMMENT: URL:http://pcts.princeton.edu/pcts/20YearsAdSCFT/20Years2017.html END:VEVENT BEGIN:VEVENT UID:1509625800848d6c35730ad0eb225a96e1943db197@sns.ias.edu DTSTART:20171102T123000Z DTEND:20171102T210000Z SUMMARY:PCTS Program, "20 Years Later: The Many Faces of AdS/CFT" DESCRIPTION:

**The first day of the conference, October 31, 2017, will be held in McDonnell Hall, Room A02.**

**On November 1, 2, 3, the conference will be held in Room 407 Jadwin Hall.**

Much of our current understanding of quantum gravity and of strongly coupled gauge theory comes from the AdS/CFT correspondence. This workshop celebrates the 20th anniversary of AdS/CFT. We will take stock of the past 20 years of progress in understanding the holographic dictionary, applications of the correspondence, implications for quantum gravity and strongly coupled field theories, as well as using lessons from AdS/CFT to understand holographic quantum gravity in a more general context.

LOCATION: COMMENT: URL:http://pcts.princeton.edu/pcts/20YearsAdSCFT/20Years2017.html END:VEVENT BEGIN:VEVENT UID:1509712200848d6c35730ad0eb225a96e1943db197@sns.ias.edu DTSTART:20171103T123000Z DTEND:20171103T210000Z SUMMARY:PCTS Program, "20 Years Later: The Many Faces of AdS/CFT" DESCRIPTION:

**The first day of the conference, October 31, 2017, will be held in McDonnell Hall, Room A02.**

**On November 1, 2, 3, the conference will be held in Room 407 Jadwin Hall.**

Holographic theories representing black holes are expected to exhibit quantum chaos. If the laws of quantum mechanics are expected to hold for observers inside such black holes, then such holographic theories must have a mean field approximation valid for typical black hole states, and for timescales approaching the scrambling time. Using simple spin models as examples, the predictions of such an approach for observers inside black holes, and more speculatively inside cosmological horizons are examined.

LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151007940016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20171107T183000Z DTEND:20171107T200000Z SUMMARY:High Energy Theory Seminar, "Uncovering Flavor of N SCFTs Through Geometry" (Matteo Lotiti, University of Cincinnati) DESCRIPTION:I will present a novel classification of 4d rank-1N Superconformal Field Theories (SCFTs), based purely on topological data. We study the low energy effective theory of N SCFTs exploiting the structure of the moduli spaces of vacua these theories possess. We extend work done in the context of F-theory constructions, analyzing the topological data encoded on the Coulomb Branch of N SCFTs. This allows us to derive the flavor structures forthe rank-1 theories. In the talk I will describe the original F-theory construction and our generalization to arbitrary rank-1 N SCFTs, presenting the results, open questions, and possible extensions of our approach.

LOCATION:Jadwin Hall, Room A06 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151008840007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20171107T210000Z DTEND:20171107T220000Z SUMMARY:Pheno & Vino Seminar, "Respect the ELDER: New Thermal Target for Dark Matter Direct Detection & Going Beyond with Neutron Star Mergers!" (Yu-dai Tsai, Cornell University) DESCRIPTION:We present a novel dark matter (DM) candidate, Elastically Decoupling Relic (ELDER), in which the DM current-day abundance is mostly determined via the elastic scattering between standard model particles and DM. ELDER has a distinctive thermal history and new phenomenological implications in comparison to the usual CDM scenarios. ELDER provides solid predictions for both next-generation direct-detection experiments and dark photon searches.

If time permits, I will talk briefly about the gravitational-wave (mergers), optical (kilonovae), and radio signatures of DM-induced neutron star (NS) Implosions. The astrophysical signatures are ways to go orders-of-magnitude beyond the DM direct-detection limits, demonstrated using superheavy asymmetric DM as an example. The recently detected NS merger event, GW170817, provided us with the first robust data point for the statistical test.

The talk is based on Phys. Rev. Lett. 116, 221302 (arXiv:1512.04545), JHEP, 08:078, 2017 (arXiv:1706.05381), and arXiv:1706.00001.

Links:

- https://arxiv.org/abs/1512.04545

- (link is external)https://arxiv.org/abs/1706.05381 (link is external)

- https://arxiv.org/abs/1706.00001 (link is external)

Modern methods for computing scattering amplitudes getenormous mileage out of knowledge of (or, often, even assumptions about) their singularity structure. I will demonstrate how, in the case of N=4 SYM theory, information about this singularity structure can be derived via combinatorial geometry problems using theamplituhedron. Results of such calculations provide the basic input to the "amplitude bootstrap" program.LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1510261200c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20171109T210000Z DTEND:20171109T220000Z SUMMARY:Hamilton Colloquium Series, "Topological Quantum Chemistry" (B. Andrei Bernevig, Princeton University) DESCRIPTION:

The fields of Physics and Chemistry approach electronic band structure differently. Physicists develop an understanding of bands in momentum space, while chemists look at the bonding of orbitals in real space. For years, electronic band theory has been dominated by important quantitative aspects such as the relative energy of bands in materials composed of chemical elements sitting on lattice sites. In the 1980s and in the early 2000s Joshua Zak, and then Louis Michel, Henri Bacry and Zak made the huge, but not well-known, leap of understanding the qualitative connection between real space and momentum space. For the classical (spinless) groups, they defined the connection between orbitals of elements sitting in lattice positions and bands in momentum space. They taught us to think of a band as a representation and showed that all bands fall in blocks akin to “irreducible representations” in group theory, called Elementary Band Representations (EBRs); they also presented proofs that EBRs are connected in the Brillouin zone — they cannot be decomposed in smaller sub-bands. In this colloquium, we present work that first completes Zak’s idea by extending it to the double (spinful) groups in the presence of time-reversal. We identify what lattice positions and what orbital representations are “special” and classify all the (~10,000) elementary band representations possible in the 230 space single and double groups, with and without Time-Reversal symmetry. These are now tabulated on the Bilbao Crystallographic Server, the premier crystallography website. We then move beyond the work of Zak and collaborators by bringing topological insulators and topological semimetals into the theory of band representations. Crucially, we realize that the Elementary Band Representations, the irreducible representations of band theory, can actually be “reduced” or decomposed — different from the initial prediction; however, when they decompose, they necessarily become topological. We present a mapping of bands in the Brillouin zone to graph theory that allows us to compute whether an EBR is connected or disconnected, and classify all the EBRs existent in nature — also now tabulated on the Bilbao Crystallographic Server. Many new classes of topological insulators and semimetals arise in this way. Fundamentally, this theory offers a link from real space orbitals to topological physics, allowing for the real-space design of several new types of topological materials, which we also present.

LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151033950016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20171110T184500Z DTEND:20171110T200000Z SUMMARY:High Energy Theory Seminar, "Complexity in Holography and QFT" (Shira Chapman, Perimeter Institute) DESCRIPTION:I will review the concept of quantum complexity of a state and the related holographic conjectures. I will discuss certain properties of holographic complexity, namely, the structure of divergences, the complexity of forming a thermal state, and the time dependence of complexity. I will then move to the QFT side and describe our proposal for defining the complexity in free scalar field theories for Gaussian states based on the Fubini-Study metric. This gives rise to a beautiful geometric picture where circuits are represented as trajectories on a product space of hyperbolic planes with minimal complexity circuits corresponding to geodesic lines. Despite working with quantum field theories far outside the regime where Einstein gravity duals exist, we find striking similarities between our results and the two holographic complexity proposals. If time permits, I will describe additional developments related to the complexity of thermofield double states and its time dependence.

LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151060140016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20171113T193000Z DTEND:20171113T210000Z SUMMARY:High Energy Theory Seminar, "Quantum Closed Superstring Field Theory and the Weil-Petersson Symplectic Geometry" (Roji Pius, Perimeter Institute) DESCRIPTION:String field theory is the refined definition of string theory, formulated in the language of quantum field theory. Unlike the conventional Polyakov approach, it provides a well defined prescription for computing the scattering amplitudes in string theory, even when there is mass renormalization and quantum corrections to the background. Since, string field theory is based on an action, it also has the potential to open the door towards the nonperturbative regime of string theory. Unfortunately, the biggest problem of closed string field theory is that simple tools for performing calculations are not readily available. In this talk, I shall a discuss a calculable realization of closed superstring field theory, formulated by exploring the significant progress in the Weil-Petersson geometry of the moduli space of Riemann surfaces in recent years.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1510671600c7bc892a17c0e13e145bb32960bfdab7@sns.ias.edu DTSTART:20171114T150000Z DTEND:20171114T160000Z SUMMARY:Special Simons/PCTS Seminar, "Investigating Singularities with Numerical Relativity" (Markus Kunesch, Queen Mary University of London) DESCRIPTION:Our recent numerical simulations demonstrated that in higher dimensions even asymptotically flat black holes can break and give rise to naked singularities. This shows that if cosmic censorship were to hold in our universe, it would be a special property of four dimensional spacetimes. I will describe these results and outline other applications of the same numerical relativity code to cosmology, astrophysics, and AdS/CFT.

LOCATION:Jadwin Hall, Room 401 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151068420016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20171114T183000Z DTEND:20171114T200000Z SUMMARY:High Energy Theory Seminar, "6j Symbols and Conformal Blocks" (Petr Kravchuk, Caltech) DESCRIPTION:I will explain how conformally-covariant differential operators arise from finite-dimensional representations of the (global) conformal group. When combined with other conformal objects, such as tensor structures, these operators satisfy a number of useful identities, which, in particular, allow to express any conformal block as a differential operator acting a scalar conformal block. They also simplify the calculation of many other conformally-invariant quantities, such as shadow coefficients, crossing kernels, etc. This talk is based on 1706.07813 and work in progress.

LOCATION:Jadwin Hall, PCTS Seminar Room, Room 407 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151069320007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20171114T210000Z DTEND:20171114T220000Z SUMMARY:Pheno & Vino Seminar, "Excluding a Thin Dark Matter Disk in the Milky Way with Gaia DR1" (Kaitlyn Schutz, University of California, Berkeley) DESCRIPTION:If a component of the dark matter has dissipative interactions, it could collapse to form a thin dark disk in our Galaxy coincident with the baryonic disk. It has been suggested that dark disks could explain a variety of observed phenomena, including mass extinction events due to periodic comet impacts. Using the first data release from the Gaia space observatory, I will present the results of a search for a dark disk via its effect on stellar kinematics in the Milky Way. I will discuss our strong new limits that disfavor the presence of a thin dark matter disk and present updated measurements on the total matter density in the solar neighborhood.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151120620016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20171120T193000Z DTEND:20171120T210000Z SUMMARY:High Energy Theory Seminar, "Loops in AdS from Hamiltonian Approach" (Lorenzo Di Pietro, Perimeter Institute) DESCRIPTION:I will discuss a method to compute 1/N corrections in large N CFTs based on the Rayleigh-Schroedinger perturbation theory for the dilatation operator. I will apply the method to the simplest examples, i.e. subsectors of large-N CFTs defined by weakly coupled scalar fields in AdS. In particular, I will derive the 1/N^2 correction to the single-trace scaling dimension in phi^3 theories, and the 1/N^4 correction to the scaling dimension of (some) double-trace operators in phi^4 theories. When possible, I will compare with existing results obtained with other methods, and I will discuss the flat-space limit of the result.

LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151181100016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20171127T193000Z DTEND:20171127T210000Z SUMMARY:High Energy Theory Seminar, "TBA" (Andrew Liam Fitzpatrick, Boston University) DESCRIPTION: LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151190280007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20171128T210000Z DTEND:20171128T220000Z SUMMARY:Pheno & Vino Seminar, "TBA" (Neal Weiner, New York University) DESCRIPTION: LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1512075600c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20171130T210000Z DTEND:20171130T220000Z SUMMARY:Hamilton Colloquium Series, "TBA" (Gilles Tarjus, Laboratory of Theoretical Physics of Condensed Matter of the Pierre et Marie Curie University) DESCRIPTION: LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151215390016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20171201T184500Z DTEND:20171201T200000Z SUMMARY:High Energy Theory Seminar, "TBA" (Zohar Komargodski, Stony Brook University) DESCRIPTION: LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151241580016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20171204T193000Z DTEND:20171204T210000Z SUMMARY:High Energy Theory Seminar, "TBA" (Sasha Zhiboedov, Harvard University) DESCRIPTION: LOCATION:Jadwin Hall, PCTS Seminar Room, 4th Floor COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:15124752001e57af7721ef7553919d734fe60745bb@sns.ias.edu DTSTART:20171205T120000Z DTEND:20171206T000000Z SUMMARY:Quantum Information and Black Holes DESCRIPTION: LOCATION:Wolfensohn Hall COMMENT:FREE, but REQUIRED REGISTRATION is available online at https://www.sns.ias.edu/quantum-information-workshop-2017/registration URL:https://www.sns.ias.edu/quantum-information-workshop-2017 END:VEVENT BEGIN:VEVENT UID:151250760007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20171205T210000Z DTEND:20171205T220000Z SUMMARY:Pheno & Vino Seminar, "TBA" (Jack Collins, University of Maryland) DESCRIPTION: LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:15125616001e57af7721ef7553919d734fe60745bb@sns.ias.edu DTSTART:20171206T120000Z DTEND:20171207T000000Z SUMMARY:Quantum Information and Black Holes DESCRIPTION: LOCATION:Wolfensohn Hall COMMENT:FREE, but REQUIRED REGISTRATION is available online at https://www.sns.ias.edu/quantum-information-workshop-2017/registration URL:https://www.sns.ias.edu/quantum-information-workshop-2017 END:VEVENT BEGIN:VEVENT UID:1512680400c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20171207T210000Z DTEND:20171207T220000Z SUMMARY:Hamilton Colloquium Series, "Dipolar Quantum Gases and Liquids" (Tilman Pfau, Universität Stuttgart) DESCRIPTION:Dipolar interactions are fundamentally different from the usual van der Waals forces in real gases. Besides the anisotropy the dipolar interaction is nonlocal and as such allows for self organized structure formation. Candidates for dipolar species are polar molecules, Rydberg atoms and magnetic atoms. More than ten years ago the first dipolar effects in a quantum gas were observed in an ultracold Chromium gas. By the use of a Feshbach resonance a purely dipolar quantum gas was observed three years after. By now dipolar interaction effects have been observed in lattices and also for polar molecules. Recently it became possible to study degenerate gases of lanthanide atoms among which one finds the most magnetic atoms. The recent observation of their collisional properties includes the emergence of quantum chaos and very broad resonances. Similar to the Rosensweig instability in classical magnetic ferrofluids self-organized structure formation was expected. In our experiments with quantum gases of Dysprosium atoms we could recently observe the formation of a droplet crystal (see figure). In contrast to theoretical mean field based predictions the superfluid droplets did not collapse. We find that this unexpected stability is due to beyond meanfield quantum corrections of the Lee-Huang-Yang type. We observe and study self-bound droplets which can interfere with each other. These droplets are 100 million times less dense than liquid helium droplets and open new perspectives as a truly isolated quantum system.

LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151302060016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20171211T193000Z DTEND:20171211T210000Z SUMMARY:High Energy Theory Seminar, "TBA" (Kurt Hinterbichler, Case Western Reserve University) DESCRIPTION:

Embryology at the beginning of the 21st century finds itself in a situation similar to neurobiology; the behavior of the component pieces is understood in some detail, but how they self-assemble to become life is still very hazy. There are hundreds of molecules that enable cell communication and genetics defines their function by classifying aberrant embryos at a suitable intermediate stage of development, which is difficult for mammals and impossible for humans. Embryonic stem cells can be expanded indefinitely and in the context of the embryo give rise to all cells in the body. The colloquium will describe synthetic systems that coax these stem cells to recapitulate aspects of gastrulation, which is the process by which the embryo transforms from a sphere to a cylinder, builds its anterior-posterior and dorsal-ventral axes, and segregates cells into ectoderm (skin and neurons), mesoderm (muscle bones and blood), and endoderm (gut, lungs, pancreas, etc.) lineages.

LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1513299600fd14b45b696084b1b50fbc79f50119ab@sns.ias.edu DTSTART:20171215T010000Z DTEND:20171215T020000Z SUMMARY:Raymond and Beverly Sackler Lecture in Astrophysics, "Fast Radio Bursts" (Victoria Kaspi, McGill University) DESCRIPTION:In 2007, astronomers discovered a new mysterious cosmic phenomenon: Fast Radio Bursts. These events consist of short, intense blasts of radio waves arriving from far outside our Milky Way galaxy. Their origin is unknown, however Fast Radio Bursts appear ubiquitous in our Universe, with roughly 1000 arriving every day over the full sky. I will discuss the Fast Radio Burst mystery and what is presently known about it, and describe a revolutionary new radio telescope being built in Canada that will soon enable astronomers worldwide to make major progress in our understanding of the FRB puzzle.

LOCATION:McDonnell A02 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151613640007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20180116T210000Z DTEND:20180116T220000Z SUMMARY:Pheno & Vino Seminar, "TBA" (Kohsaku Tobioka, Stony Brook University) DESCRIPTION: LOCATION:Jadwin Hal, Room 303 COMMENT: URL: END:VEVENT END:VCALENDAR