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, "Information Loss and Bulk Reconstruction in AdS_3/CFT_2" (Andrew Liam Fitzpatrick, Boston University) DESCRIPTION:We discuss how to obtain dynamics of semiclassical gravity in 3d AdS from the large central charge limit of irreducible representations of the conformal algebra of 2d CFTs, with a focus on black hole information loss and bulk reconstruction. We describe recent and ongoing work to extract “non-perturbative” (in Newton’s constant) gravitational effects from the exact behavior of such irreps at large but finite central charge.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151190280007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20171128T210000Z DTEND:20171128T220000Z SUMMARY:Pheno & Vino Seminar, "Signals of a Lighter Higgs (?)" (Neal Weiner, New York University) DESCRIPTION:As the LHC has neared peak energy with sizable luminosity, an open question remains where surprises may yet appear. One possibility is within searches for Higgses at masses below the SM-like Higgs at 125 GeV. I will discuss both singlet and doublet models that could yet appear. Piqued by a recent excess in the CMS search for diphoton resonances, I will review what excesses lay unexplained, including in LEP data, in tth, as well as diphoton, and possible models to explain them.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1512075600c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20171130T210000Z DTEND:20171130T220000Z SUMMARY:Hamilton Colloquium Series, "The Glass Transition: A Theoretical Perspective" (Gilles Tarjus, Laboratory of Theoretical Physics of Condensed Matter of the Pierre et Marie Curie University) DESCRIPTION:When cooled fast enough to avoid crystallization, a liquid becomes increasingly viscous and eventually forms a glass. This “glass transition,” one of the oldest unsolved problems in condensed-matter physics, gives rise to a wide diversity of views. Accordingly, there is a lack of agreement on which would be the most profitable theoretical approach. I will briefly describe the main pieces of the phenomenology and then discuss the progress made in the last decade, including new insights concerning the characteristic length scales associated with the glass transition. The emphasis will be placed on those theories that associate glass formation with growing collective behavior and emerging universality.

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, "Dynamics in 2+1 Dimensions" (Zohar Komargodski, Stony Brook University) DESCRIPTION:We explain recent ideas that led to rapid progress on the dynamics of gauge theories in 2+1 dimensions. We discuss gauge theories with matter particles in the fundamental as well as in the adjoint representations. We make predictions for new phases of these theories and explain some special cases where these predictions can be already verified. We emphasize some implications for N=1 supersymmetry in 2+1 dimensions and its spontaneous breakdown.

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, "Conformal Field Theories in the Regge Limit" (Alexander Zhiboedov, Harvard University) DESCRIPTION:I will review recent developments in the understanding of Lorentzian correlators in generic CFTs. I will then discuss two applications of these developments. The first one involves bounds on the OPE coefficients on the leading Regge trajectory. In theories with gravity duals, it constrains certain higher-derivative corrections to the Einstein theory. The second application is the computation of four-point functions in CFTs with weakly broken higher spin symmetry.

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:Registration is now closed for this workshop URL:https://www.sns.ias.edu/quantum-information-workshop-2017/schedule END:VEVENT BEGIN:VEVENT UID:151250760007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20171205T210000Z DTEND:20171205T220000Z SUMMARY:Pheno & Vino Seminar, "Searching for New Physics in Jets" (Jack Collins, University of Maryland) DESCRIPTION:New physics beyond the Standard Model may show up at the LHC in the form of boosted particles decaying hadronically, resulting in fat jets with unusual substructure. A simple possibility is heavy resonances decaying into pairs of boosted W, Z, and Higgs bosons which can form 2-prong fat jets, and these models are targeted by a wide range of diboson searches at the LHC. Alternatively the boosted particles may themselves be BSM particles, and these may decay in a variety of 2- or many-pronged topologies. I will firstly discuss how such scenarios might be observed as excesses in standard diboson searches, highlighting a few anomalies which illustrate the subtleties involved in interpreting these scenarios. I will then more on to the question of how to search for multi-prong fat jets coming from unknown boosted BSM particles in a model-agnostic way, describing an approach making use of machine learning of jet substructure.

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:Registration is now closed for this workshop. URL:https://www.sns.ias.edu/quantum-information-workshop-2017/schedule 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, "Constraints on Interacting Massive High Spins" (Kurt Hinterbichler, Case Western Reserve University) DESCRIPTION:There seem to be no good examples of UV complete theories that have low-lying massive higher spin states isolated by a large gap, despite the relative ease of constructing effective field theories describing such states. We discuss constraints from analytic dispersion relations and subluminality of eikonal scattering that may help to explain this and provide insight into the possible interactions of massive higher spins.

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:151336350016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20171215T184500Z DTEND:20171215T200000Z SUMMARY:High Energy Theory Seminar, "Universality of Quantum Information in Chaotic CFTs" (Nima Lashkari, Massachusetts Institute of Technology) DESCRIPTION:We study the Eigenstate Thermalization Hypothesis (ETH) in chaotic conformal field theories (CFTs) of arbitrary dimensions. Assuming local ETH, we compute the reduced density matrix of a ball-shaped subsystem of finite size in the infinite volume limit when the full system is an energy eigenstate. This reduced density matrix is close in trace distance to a density matrix, to which we refer as the ETH density matrix, that is independent of all the details of an eigenstate except its energy and charges under global symmetries. In two dimensions, the ETH density matrix is universal for all theories with the same value of central charge. We argue that the ETH density matrix is close in trace distance to the reduced density matrix of the (micro)canonical ensemble. We support the argument in higher dimensions by comparing the Von Neumann entropy of the ETH density matrix with the entropy of a black hole in holographic systems in the low temperature limit. Finally, we generalize our analysis to the coherent states with energy density that varies slowly in space, and show that locally such states are well described by the ETH density matrix.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:15154182003c11a39d4a3e680d3b72ff2b75cab2eb@sns.ias.edu DTSTART:20180108T133000Z DTEND:20180108T223000Z SUMMARY:PCTS Workshop, "Gravity in the Early Universe" DESCRIPTION:**Program Organizers: **Anna Ijjas (Columbia), Frans Pretorius (Princeton), Paul J. Steinhardt (Princeton-PCTS)

This workshop will focus on modifications of Einstein gravity at high (but sub-Planckian) energy densities that would influence the dynamics and evolutionary history of the early universe. Of particular interest are a variety of recent proposals for avoiding the cosmological singularity by stably violating the null energy condition while remaining in the regime of validity of classical field theories. Understanding these approaches requires the development of new ideas, new analytical tools, and new numerical techniques. The goal is to bring together leading experts in cosmology and general relativity to explore these ideas.

We will have only five speakers and each will be given two 1.5 hour slots, so that there is time for a more pedagogical presentation and lots of time for questions and interaction during and after.

LOCATION:Jadwin Hall, PCTS Seminar Room, Room 407 COMMENT:FREE, but REQUIRED REGISTRATION is limited and available online at http://pcts.princeton.edu/pcts URL:http://wwwphy.princeton.edu/pcts/GravityEarlyUniverse2017/GravityEarlyUniv2017.html END:VEVENT BEGIN:VEVENT UID:15155046003c11a39d4a3e680d3b72ff2b75cab2eb@sns.ias.edu DTSTART:20180109T133000Z DTEND:20180109T223000Z SUMMARY:PCTS Workshop, "Gravity in the Early Universe" DESCRIPTION:**Program Organizers: **Anna Ijjas (Columbia), Frans Pretorius (Princeton), Paul J. Steinhardt (Princeton-PCTS)

This workshop will focus on modifications of Einstein gravity at high (but sub-Planckian) energy densities that would influence the dynamics and evolutionary history of the early universe. Of particular interest are a variety of recent proposals for avoiding the cosmological singularity by stably violating the null energy condition while remaining in the regime of validity of classical field theories. Understanding these approaches requires the development of new ideas, new analytical tools, and new numerical techniques. The goal is to bring together leading experts in cosmology and general relativity to explore these ideas.

We will have only five speakers and each will be given two 1.5 hour slots, so that there is time for a more pedagogical presentation and lots of time for questions and interaction during and after.

LOCATION:Jadwin Hall, PCTS Seminar Room, Room 407 COMMENT:FREE, but REQUIRED REGISTRATION is limited and available online at http://pcts.princeton.edu/pcts URL:http://wwwphy.princeton.edu/pcts/GravityEarlyUniverse2017/GravityEarlyUniv2017.html END:VEVENT BEGIN:VEVENT UID:151553160007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20180109T210000Z DTEND:20180109T220000Z SUMMARY:Pheno & Vino Seminar, "Recent Results from the MAJORANA DEMONSTRATOR neutrinoless Double-beta Decay Search" (Graham Govanetti, Princeton University) DESCRIPTION:The MAJORANA DEMONSTRATOR is an array of high purity germanium detectors searching for the neutrinoless double-beta decay of Ge-76. The array is currently operating within a low background shield at the Sanford Underground Research Facility in Lead, SD. I will present recent results from the first dataset collected with the DEMONSTRATOR that show unprecedented energy resolution and very low background rates, resulting in a lower limit on the neutrinoless double-beta decay half-life of 1.9E25 years.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:15155910003c11a39d4a3e680d3b72ff2b75cab2eb@sns.ias.edu DTSTART:20180110T133000Z DTEND:20180110T223000Z SUMMARY:PCTS Workshop, "Gravity in the Early Universe" DESCRIPTION:**Program Organizers: **Anna Ijjas (Columbia), Frans Pretorius (Princeton), Paul J. Steinhardt (Princeton-PCTS)

This workshop will focus on modifications of Einstein gravity at high (but sub-Planckian) energy densities that would influence the dynamics and evolutionary history of the early universe. Of particular interest are a variety of recent proposals for avoiding the cosmological singularity by stably violating the null energy condition while remaining in the regime of validity of classical field theories. Understanding these approaches requires the development of new ideas, new analytical tools, and new numerical techniques. The goal is to bring together leading experts in cosmology and general relativity to explore these ideas.

We will have only five speakers and each will be given two 1.5 hour slots, so that there is time for a more pedagogical presentation and lots of time for questions and interaction during and after.

LOCATION:Jadwin Hall, PCTS Seminar Room, Room 407 COMMENT:FREE, but REQUIRED REGISTRATION is limited and available online at http://pcts.princeton.edu/pcts URL:http://wwwphy.princeton.edu/pcts/GravityEarlyUniverse2017/GravityEarlyUniv2017.html END:VEVENT BEGIN:VEVENT UID:151578270016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180112T184500Z DTEND:20180112T200000Z SUMMARY:High Energy Theory Seminar, "Genomic Prediction of Complex Traits" (Steve Hsu, Michigan State University) DESCRIPTION:After a brief review (suitable for physicists) of computational genomics and complex traits, I describe recent progress in this area.

Using methods from Compressed Sensing (L1-penalized regression; Donoho-Tanner phase transition with noise) and the UK BioBank dataset of 500k SNP genotypes, we construct genomic predictors for several complex traits. Our height predictor captures nearly all of the predicted SNP heritability for this trait -- thereby resolving the missing heritability problem. Actual heights of most individuals in validation tests are within a few cm of predicted heights. I also discuss application of these methods to cognitive ability and polygenic disease risk: sparsity estimates (of the number of causal loci), combined with phase transition scaling analysis, allow estimates of the amount of data required to construct good predictors.

Finally, I discuss how these advances will affect human health and reproduction (embryo selection for In Vitro Fertilization, genetic editing) in the coming decade.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1516028400e672d045abcf51f702d136442ba0d4de@sns.ias.edu DTSTART:20180115T150000Z DTEND:20180115T170000Z SUMMARY:PCTS Event, "Triggering on New Physics at the HL-LHC" DESCRIPTION:The LHC community is now moving toward its final phase of experimental design, the Phase 2 Upgrade for the High-Luminosity LHC. A critical step in defining the capabilities of new physics searches at the HL-LHC has begun with the definition of the Phase 2 trigger upgrades. The experimental work on these systems will achieve sufficient maturity by the end of 2017, making this an ideal time for the experimental and theory communities to re-evaluate current strategies. This is a critical time to develop new trigger definitions that address the many exciting new ideas being developed by the phenomenology community. The strategies developed in this meeting will have a substantial impact on what new physics is recorded by the detectors and will ultimately inform our understanding of the physics accessible at the high-energy frontier.

LOCATION:Jadwin Hall, PCTS-Seminar Room 407 COMMENT: URL:https://indico.cern.ch/event/678456/overview END:VEVENT BEGIN:VEVENT UID:1516113000e672d045abcf51f702d136442ba0d4de@sns.ias.edu DTSTART:20180116T143000Z DTEND:20180116T220000Z SUMMARY:PCTS Event, "Triggering on New Physics at the HL-LHC" DESCRIPTION:The LHC community is now moving toward its final phase of experimental design, the Phase 2 Upgrade for the High-Luminosity LHC. A critical step in defining the capabilities of new physics searches at the HL-LHC has begun with the definition of the Phase 2 trigger upgrades. The experimental work on these systems will achieve sufficient maturity by the end of 2017, making this an ideal time for the experimental and theory communities to re-evaluate current strategies. This is a critical time to develop new trigger definitions that address the many exciting new ideas being developed by the phenomenology community. The strategies developed in this meeting will have a substantial impact on what new physics is recorded by the detectors and will ultimately inform our understanding of the physics accessible at the high-energy frontier.

LOCATION:Jadwin Hall, PCTS-Seminar Room 407 COMMENT: URL:https://indico.cern.ch/event/678456/overview END:VEVENT BEGIN:VEVENT UID:151613100016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180116T193000Z DTEND:20180116T210000Z SUMMARY:High Energy Theory Seminar, "Decoding a Black Hole" (Beni Yoshida, Perimeter Institute) DESCRIPTION:It is commonly believed that quantum information is not lost in a black hole. Instead, it is encoded into non-local degrees of freedom in some clever way; like a quantum error-correcting code. In this talk, I will present two decoding procedures for reconstructing a quantum state from the Hawking radiation in the Hayden-Preskill thought experiment. The first procedure teleports the state thrown into the black hole to an outside observer by post-selecting on the condition that a sufficient number of EPR pairs remain undisturbed. The second procedure is deterministic and combines the previous idea with Grover’s search algorithm. As with the original (non-constructive) decoding scheme, the algorithms utilize scrambling, where the decay of out-of-time-order correlators (OTOCs) guarantees faithful state recovery. Decoding protocols also provide an ideal platform for laboratory experiments to measure out-of-time ordered correlation functions in a way which clearly distinguish unitary scrambling from decoherence. I will conclude by introducing an ongoing experiment in a small quantum system.

LOCATION:Jadwin Hall, Room A09 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1516201200e672d045abcf51f702d136442ba0d4de@sns.ias.edu DTSTART:20180117T150000Z DTEND:20180117T220000Z SUMMARY:PCTS Event, "Triggering on New Physics at the HL-LHC" DESCRIPTION:The LHC community is now moving toward its final phase of experimental design, the Phase 2 Upgrade for the High-Luminosity LHC. A critical step in defining the capabilities of new physics searches at the HL-LHC has begun with the definition of the Phase 2 trigger upgrades. The experimental work on these systems will achieve sufficient maturity by the end of 2017, making this an ideal time for the experimental and theory communities to re-evaluate current strategies. This is a critical time to develop new trigger definitions that address the many exciting new ideas being developed by the phenomenology community. The strategies developed in this meeting will have a substantial impact on what new physics is recorded by the detectors and will ultimately inform our understanding of the physics accessible at the high-energy frontier.

LOCATION:Jadwin Hall, PCTS-Seminar Room 407 COMMENT: URL:https://indico.cern.ch/event/678456/overview END:VEVENT BEGIN:VEVENT UID:151621740016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180117T193000Z DTEND:20180117T210000Z SUMMARY:High Energy Theory Seminar, "Symmetries in Quantum Field Theory" (Clay Cordova, Institute for Advanced Study) DESCRIPTION:Symmetry underlies the foundations of quantum field theory, defining concepts like particles and helping to organize their properties. In this talk I will illustrate several modern topics in the study of symmetry including infinite-dimensional representations in conformal field theory, constraints of current algebra and energy conditions, and the interplay of symmetry and topology. I will also describe how some of these techniques can be applied to understand Abelian gauge theories in 2+1 dimensions with time-reversal symmetry.

LOCATION:Jadwin Hall, PCTS Seminar Room 407 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1516309200c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20180118T210000Z DTEND:20180118T220000Z SUMMARY:Hamilton Colloquium Series, "The Higgs Portal onto the Dark Universe" (Jessie Shelton, University of Ilinois (Urbana-Champaign)) DESCRIPTION:The Standard Model of particle physics has been a smashing success at the high energies newly tested at the Large Hadron Collider (LHC). The LHC's discovery of the Higgs boson completes the Standard Model and bears out one of its most puzzling predictions. I will explain why we know the Standard Model must be incomplete, and how the Higgs boson can give important clues about several remaining mysteries of our universe. These observations will help inform future directions in the search for physics beyond the Standard Model.

LOCATION:Jadwin Hall, Room A07 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151638480007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20180119T180000Z DTEND:20180119T200000Z SUMMARY:Pheno & Vino Seminar, "Hunt for Low Mass Diphoton Resonance at LHC and Beyond" (Kohsaku Tobioka, Stony Brook University) DESCRIPTION:I discuss new strategies to hunt for a resonance in diphoton final state. First, I present a new bound on diphoton resonances using inclusive diphoton cross section measurements at the LHC (ATLAS and CMS), in the so-far poorly constrained mass range between the Υ and the SM Higgs. This bound sets the current best limit on axion-like particles that couple to gluons and photons, for masses between 10 and 65 GeV. Also, we estimated indicative sensitivities of a dedicated diphoton LHC search in the same mass region, at 7, 8 and 14 TeV. For a lighter resonance below 10GeV, as preliminary studies, I discuss future searches for the resonance at the LHCb detector and Kaon factories such as KOTO and NA62.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1516741200615e3b586811f0fae382c76390977e8f@sns.ias.edu DTSTART:20180123T210000Z DTEND:20180123T220000Z SUMMARY:Pheno and Vino Seminar, "Natural Seesaw in Warped/Composite Higgs framework and its LHC Signals" (Kaustubh Agashe, University of Maryland) DESCRIPTION:I will show how a natural seesaw model for SM neutrino mass arises within the general framework of a warped extra dimension (dual to composite Higgs in 4D). It starts out as an attempt at implementing the high-scale seesaw mechanism. I will first carefully determine what the underlying dynamical picture really is. Motivated by this physical understanding, LHC signals of TeV-mass SM singlet neutrinos within a specific model for the electroweak gauge sector will be discussed. Some of these channels are similar to those studied in 4D left-right (LR) symmetric models, but nonetheless the two can be distinguished. While other signals are more characteristic of the 5D/composite framework, i.e., are absent in 4D LR models.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:15169050008b8f6052ab01a5e5e363edaaf7fb77b5@sns.ias.edu DTSTART:20180125T183000Z DTEND:20180125T200000Z SUMMARY:Special Physics Seminar, "Fantastic Emergent Orders and Where to Find Them" (Ming Yi, University of California, Berkeley) DESCRIPTION:Spontaneous emergence of orders is a recurring theme in physics that occurs at many different length scales. These orders emerge not because of the characteristics of the individual constituents, but because of the interactions amongst the participants that result in fantastically interesting collective behaviors. As an experimental condensed matter physicist, I study interactions occurring at the atomic scale of material systems, where quantum effects lead to orderings of the lattice, charge, spin and orbital degrees of freedom, often macroscopically manifested in material properties for real-world applications. In this talk, I will use the material system of the iron-based high temperature superconductors to illustrate the range of exotic electronic orders that have been discovered in recent years. In doing so, we come to appreciate the spectacularly bustling landscape of electronic phases out of which the enigmatic phenomenon of high temperature superconductivity arises.

LOCATION:Jadwin Hall, Room A07 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:15169914008b8f6052ab01a5e5e363edaaf7fb77b5@sns.ias.edu DTSTART:20180126T183000Z DTEND:20180126T200000Z SUMMARY:Special Physics Seminar, "Correlated States in Graphene Double-layer in the Quantum Hall Regime" (Jia (Leo) Li, Columbia University) DESCRIPTION:The technique of layer-by-layer van der Waals (vdW) heterostructure allows any 2D material exfoliated from a bulk crystal to be reassembled into a designer architecture, making it possible to study the coupling and interplay between different emergent quantum phenomena through engineering new meta-materials. An example of such meta-material is the double-layer graphene heterostructure, two vertically aligned graphene separated by a thin layer of hexagonal boron nitride (hBN). In the quantum Hall effect regime, tuning both graphene layers to half filling of the lowest Landau level induces interlayer excitonic coupling, forming an equivalent system of indirect excitons. I will show that such system undergoes a Berezinskii-Kosterlitz-Thouless (BKT) type phase transition at low temperature into a ground state with quasi-long range order. Recent measurements also revealed ground states with interlayer coherence appearing at fractional filling nu=p/q, with q being either an even or odd integer. The strength of interlayer and intralayer interaction can be tuned with magnetic field, interlayer separation, filling fractions and density imbalance, providing us with a multi-dimensional phase space to study these novel ground states, and access to the so-called “BEC-BCS crossover” regime. To conclude, I will discuss possible research directions in vdW heterostructure moving forward.

LOCATION:Jadwin Hall, Room A07 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:15172416008b8f6052ab01a5e5e363edaaf7fb77b5@sns.ias.edu DTSTART:20180129T160000Z DTEND:20180129T170000Z SUMMARY:Special Physics Seminar, "Quantum Control as a Resource for Fundamental Physics and Technology" (Christian Schneider, University of California, Los Angeles) DESCRIPTION:Precise control over quantum systems is the foundation of quantum technology that will shape our society in revolutionary ways—from computation and simulation to sensing and communication. Alongside technological advances, better and better quantum control will enable new tests of fundamental physics. I will discuss our efforts on both fundamental physics and technological aspects.

First, I will focus on our work with cold atoms and ions in a hybrid atom-ion setup. An integrated time-of-flight mass spectrometer allows for the analysis of ion ensembles with isotopic resolution. Recent results will be highlighted such as the demonstration of non-equilibrium physics between atoms and ions as well as the discovery of a new class of molecules. Ultimately, this work aims at a quantum computation platform utilizing cold molecular ions.

Second, I will report on our search for the nuclear isomeric transition in thorium-229. This transition around 160nm eludes nuclear physics techniques but becomes accessible to lasers and is a prime candidate for future optical clocks and fundamental physics tests. In a first direct search using thorium-doped crystals and tunable VUV synchrotron light, we were able to exclude a large region of transition frequencies vs. lifetimes. Our ongoing efforts with a home-built VUV laser system will yield significantly improved sensitivity.

Lastly, future directions will be outlined using novel quantum systems with far-reaching impact on metrology, quantum sensing, quantum computation, quantum chemistry, and fundamental physics tests.

LOCATION:Jadwin Hall, Room A07 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1517346000fb81543489ee08b213b6fccd574d080e@sns.ias.edu DTSTART:20180130T210000Z DTEND:20180130T220000Z SUMMARY:Pheno & Seminar, "Resonant Absorption of Dark Matter in Molecules" (Ken Van Tilberg, Institute for Advanced Study & New York University) DESCRIPTION:I will present a proposal for a new class of bosonic dark matter (DM) detectors based on resonant absorption onto a gas of small polyatomic molecules. Bosonic DM acts on the molecules as a narrow-band perturbation, like an intense but weakly coupled laser.

The excited molecules emit the absorbed energy into fluorescence photons that are picked up by sensitive photodetectors with low dark count rates. This setup is sensitive to any DM candidate that couples to electrons, photons, and nuclei, and may improve on current searches by several orders of magnitude in coupling for DM masses between 0.2 eV and 20 eV. This type of detector has excellent intrinsic energy resolution, along with several control variables---pressure, temperature, external electromagnetic fields, molecular species/isotopes---that allow for powerful background rejection methods as well as precision studies of a potential DM signal. The proposed experiment does not require usage of novel exotic materials or futuristic technologies, relying instead on the well-established field of molecular spectroscopy, and on recent advances in single-photon detection. Cooperative radiation effects, which arise due to the large spatial coherence of the nonrelativistic DM field in certain detector geometries, can tightly focus the DM-induced fluorescence photons in a direction that depends on the DM's velocity, permitting a detailed reconstruction of the full 3D velocity distribution in our Galactic neighborhood, as well as further background rejection.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151785900016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180205T193000Z DTEND:20180205T210000Z SUMMARY:High Energy Theory Seminar, "CFT Data at Large Charge from EFT" (Riccardo Rattazzi, CERN) DESCRIPTION:Properties of CFT operators carrying some large global charge can be systematically computed in a 1/Q expansion by assuming that the corresponding states on the cylinderare described by a supefluid phase. In particular one can compute the spectrum of such “heavy" operators and the heavy-heavy-light fusion coefficients. The key to computational control is the effective field theory for the superfluid phase. This is universally described by a goldstone boson in a systematic derivative expansion, which corresponds to the 1/Q expansion. By plausibly assuming that the superfluid supports vortex excitations one can also derive properties of the operators carrying both large charge and large spin.LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151794360016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180206T190000Z DTEND:20180206T200000Z SUMMARY:High Energy Theory Seminar, "Twistor and Spinor-helicity Languages for the Free-CFT Dual of Higher-spin Gravity" (Yasha Neiman, Okinawa Institute of Science and Technology) DESCRIPTION:

The Penrose transform maps between functions in twistor space and solutions to free massless field equations in 4d. Higher-spin gravity is the ultimate massless 4d theory, which allows a unique geometric perspective on the Penrose transform, as I will describe. I then describe a "holographic dual" of the Penrose transform, which maps between twistor functions and the sources/operators of the free 3d vector model dual to higher-spin gravity. Twistor space thus serves as a non-local, gauge-invariant common language, underlying both the bulk and boundary theories. Finally, I consider a positive cosmological constant, where higher-spin symmetry is partially broken by picking out a causal patch in de Sitter space. This leads to an efficient spinor-helicity formalism, which should provide a powerful tool for understanding higher-spin dS/CFT.

LOCATION:Jadwin Hall, Room A06 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151795080007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20180206T210000Z DTEND:20180206T220000Z SUMMARY:Pheno & Vino Seminar, "Digging Deeper for New Physics in the LHC Data" (David Shih, Rutgers University) DESCRIPTION:A typical new physics search by CMS can now have hundreds of exclusive signal regions. While this has the potential for great discriminating power, it can also obscure potentially interesting discrepancies if they do not occur in the handful of signal regions that are probed by a small set of simplified models used by the analysis. In this talk, I will review two recent papers (1707.05783 and 1712.04939), where we developed new, model-independent methods to mine the public LHC results for interesting anomalies. Using these methods, we uncovered a number of statistically significant excesses in the LHC SUSY searches that have been previously overlooked. One of the most promising excesses arises consistently in both CMS jets+MET searches, as well as the most recent ATLAS monojet search, and is characterized by low jet multiplicity, zero b-jets, and low MET and HT. We show that resonant color-triplet production decaying to a quark plus an invisible particle provides an excellent fit to this "monojet excess" with 3.3σ (2.5σ) local (global) significance. We also describe additional cuts that could potentially increase the significance of the excess. Based on these results, we believe the wide-spread view that the LHC data contains no interesting excesses is greatly exaggerated.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1518029100ddcbf452bffff0a1f9a416202b44514a@sns.ias.edu DTSTART:20180207T184500Z DTEND:20180207T200000Z SUMMARY:Physics Group Meeting, "Modular Berry Connection" (Bartlomiej Czech, Institute for Advanced Study) DESCRIPTION:Many quantities in the AdS/CFT correspondence, for example entanglement entropies, are defined up to a choice of UV cutoff. The cutoff can be chosen and adjusted depending on one's purposes; it represents a sort of gauge freedom. I will explain that this gauge freedom leads to physical consequences in a way that closely mirrors the construction of the Berry phase. In Berry's language, the control space is the kinematic space (the space of pairs of points) in CFT2 and the changing Hamiltonians are the modular Hamiltonians of the intervals. The modular Berry "phase" is actually a "Berry normalization"; it acts on OPE blocks / geodesic operators in the bulk of AdS3 by a multiplicative constant, which equals (the exponential of) the length of the bulk curve selected by a given closed trajectory in kinematic space. I will sketch a few generalizations and potential applications of modular Berry phases.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1518123600c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20180208T210000Z DTEND:20180208T220000Z SUMMARY:Hamilton Colloquium Series, "The Social Life of Heavy Quarks" (Marek Karliner, Tel-Aviv University) DESCRIPTION:I will discuss recent developments regarding new types of hadrons involving heavy quarks: hadronic molecules, doubly heavy baryons, stable tetraquarks and others. I will also explain how the discovery of the doubly heavy baryon leads to quark-level analogue of nuclear fusion, with energy release per reaction an order of magnitude greater than in ordinary fusion.

LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151820190016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180209T184500Z DTEND:20180209T194500Z SUMMARY:High Energy Theory Seminar, "Localization on Seifert Manifolds" (Brian Willett, University of California, Santa Barbara) DESCRIPTION:I discuss the partition functions of supersymmetric gauge theories on Seifert manifolds. First we consider the case of 3d N=2 theories on a three-manifold $M_{g,p}$, a degree-p principal U(1) bundle over a smooth, genus-g Riemann surface. This includes the topological index and the three-sphere and lens space partition functions as special cases. The computation can be performed using a 3d uplift of the A-twist on the underlying Riemann surface. A similar calculation for 4d N=1 theories on $M_{g,p}$ x $S^1$ is also described. I discuss several applications of these computations, and briefly comment on the extension to arbitrary Seifert manifolds, i.e., circle bundles over orbifolds.

LOCATION:Jadwin Hall, Room A06 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151846380016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180212T193000Z DTEND:20180212T210000Z SUMMARY:High Energy Theory Seminar, "New Large N Quantum Field Theories" (Vladimir Rosenhaus, KITP, Santa Barbara) DESCRIPTION:Quantum field theories with a large number of fields offer a number of simplifications, and in some cases allow for computations at strong coupling. Two canonical examples are field theories where the fundamental fields are vectors, such as the O(N) vector model, and field theories where the fundamental fields are matrices, such as SU(N) gauge theories. We discuss a recently discovered new class of large N theories - in which the fundamental fields are neither vectors nor matrices, but tensors. In one dimension, these are part of the SYK family of models. These models enjoy the extraordinary property of having, at strong coupling, emergent conformal invariance as well as maximal chaos, while nevertheless being solvable. This unique combination allows one to construct tractable models of AdS/CFT duality and black holes, as well as of strongly correlated many body systems.

In this talk, we solve the SYK model, computing all point correlation functions. The solution has remarkable simplicity and structure. We discuss the implications for our understanding of conformal field theory, of string theory in two dimensions, and of holography and the emergence of spacetime.

LOCATION:Jadwin Hall, PCTS Seminar Room 407 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1518728400c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20180215T210000Z DTEND:20180215T220000Z SUMMARY:Hamilton Colloquium Series, "The Entanglement Glue for Spacetime" (Xiaoliang Qi, Stanford University) DESCRIPTION:Einstein’s theory of general relativity tells us that gravity comes from curved space-time geometry. The space-time is like a plastic membrane which we can stretch with our energy and momentum. But what is this membrane made of? What glues the spacetime together? These questions are not philosophical, but have to be understood in order to develop a complete theory of gravity. In particular, we need a more “microscopic” understanding of spacetime to know how quantum mechanics interplay with gravity. In recent years, progress in the field of holographic duality has shown that quantum entanglement plays a key role in “gluing” space-time together. The curved space-time geometry may emerge as an effective description of the entanglement structure in many-body quantum states. In this talk, I will describe a few toy models that illustrate this idea. I will discuss how a family of quantum states known as tensor network states naturally relate geometry and entanglement. As a more concrete dynamical model, I will discuss how to build a two-dimensional “eternal” traversable wormhole by gluing two copies of Sachdev-Ye-Kitaev (SYK) model.

LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151880670016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180216T184500Z DTEND:20180216T200000Z SUMMARY:High Energy Theory Seminar, "A Precision Study of 5d Superconformal Fixed Points" (Yifan Wang, Princeton University) DESCRIPTION:Interacting unitary conformal fixed points in five dimensions are mysterious objects which often do not have weakly coupled UV descriptions. Their conformal data such as operator spectrum and correlation functions appear more elusive to conventional methods than in lower dimensions. In this talk, we make progress towards addressing this question using supersymmetry and a combination of techniques including localization, conformal bootstrap and holography.

We first discuss subtle properties of the sphere partition function of 5d N=1 superconformal field theories (SCFT) and derive formulae for conformal and flavor central charges from its deformations. Along the way, we discover a new superconformal anomaly in five dimensions. We then focus on the rank one Seiberg-Morrison $E_n$ SCFTs, compute their central charges from IR gauge theory descriptions and clarify the notion of symmetry enhancement at the level of the sphere partition function. Finally we apply bootstrap methods to these theories and observe their saturation of the numerical bounds, which allows for solving the non-BPS spectrum. We also extend the analysis to the large (rank) N versions of these theories and compare with supergravity duals via AdS/CFT.

LOCATION:Jadwin Hall, PCTS Seminar Room 407 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151906860016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180219T193000Z DTEND:20180219T203000Z SUMMARY:High Energy Theory Seminar, "Holographic Entanglement and Poincare Blocks in Three-Dimensional Flat Space" (Charles Rabideau, University of Pennsylvania) DESCRIPTION:Inspired by a recent computation of holographic entanglement entropy in flat space holography, we proposed a covariant prescription to compute holographic entanglement entropy and Poincare blocks (Global BMS blocks) in the context of three-dimensional Einstein gravity in flat space. This prescription allows us to relate the kinematics of BMS field theories to bulk computations in an asymptotically flat space. I will first present a prescription based on worldline methods in the probe limit, inspired by analog calculations in AdS/CFT. Building on this construction, I will propose a full extrapolate dictionary and use it to compute holographic correlators and blocks away from the probe limit. I will conclude by commenting on relations between this work and other approaches in the literature.

LOCATION:Jadwin Hall, PCTS Seminar Room 407 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151915320083f9c60dbd42edcf73163f3aabf5b2e5@sns.ias.edu DTSTART:20180220T190000Z DTEND:20180220T200000Z SUMMARY:Special CM Seminar, "The Topology and Quantum Criticality in 1+1D" (Ruben Verresen, Technical University of Munich & Max Planck Institute) DESCRIPTION:Ground states of gapped Hamiltonians can form 'symmetry-protected topological phases', characterized by zero-energy edge modes. We explore the quantum critical points between such topological phases in one spatial dimension. Two main questions are addressed, namely how universal properties of the critical point are related to the nearby gapped phases, and whether critical points themselves can be topologically non-trivial. The first question leads to a topological lower bound on the central charge. The second question is answered in full for a class of non-interacting fermions (BDI), with the critical phases being classified by a topological invariant. Curiously, this invariant protects exponentially localized edge modes, even though the bulk contains no massive degrees of freedom.

LOCATION:Jadwin Hall, PCTS Seminar Room 407 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151916040007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20180220T210000Z DTEND:20180220T220000Z SUMMARY:Pheno & Vino Seminar, "The Strong CP Problem and UV Instantons" (Prateek Agrawal, Harvard University) DESCRIPTION:The absence of sizeable CP violation in the strong sector is a long standing puzzle. A class of solutions to this problem rely on a global U(1) symmetry that is anomalous with QCD. These solutions lead to robust low-energy predictions, for example a massless up quark or a light axion. I will present simple extensions to such solutions which can dramatically change these low-energy predictions. In our models, contributions from small instantons play a significant role in affecting the low-energy physics while preserving the solution to the strong CP problem.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1519333200c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20180222T210000Z DTEND:20180222T220000Z SUMMARY:Hamilton Colloquium Series, "Motifs in Morphogenesis" (Lakshminarayanan Mahadevan, Harvard University) DESCRIPTION:How is living matter organized in space and time during multicellular morphogenesis? A comparative view across animals and plants suggests that the answer may lie in reusing just a few geometric and topological organ-sculpting motifs. Using examples, I will discuss the qualitative and quantitative basis for three of these motifs: elongation, lumenization and folding.

LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151941150016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180223T184500Z DTEND:20180223T200000Z SUMMARY:High Energy Theory Seminar, "Splittability and Noether's Theorem in Quantum Field Theory" (Daniel Harlow, Massachusetts Institute of Technology) DESCRIPTION:Noether's theorem is textbook material in quantum field theory, but among experts it has been known for a while that there are quantum field theories with continuous global symmetries which possess no conserved current. In this talk I will give a few examples of this, and also describe a relationship between this phenomenon and a general property of algebraic quantum field theory called the split property. In particular we will see that violations of the split property on manifolds other than $R^d$ can prevent the existence of a Noether current on $R^d$, even if the split property holds on $R^d$. We will extend this notion to discrete global symmetries, and we will also see that all examples so far with "unsplittable" global symmetries have the property that there is a topological sector with ``unbreakable surface operators''. Finally we will conjecture that Noether's theorem, or more generally splittability of global symmetries, should hold in any quantum field theory which does not possess such a sector.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:151967340016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180226T193000Z DTEND:20180226T203000Z SUMMARY:High Energy Theory Seminar, "The Large N Melonic Limit of O(N) Tensor Models" (Sylvain Carrozza, Perimeter Institute) DESCRIPTION:It has been recently recognized that the same type of melonic large N structure governs SYK models and tensor models alike. Following Witten and Klebanov-Tarnopolsky, this has led to the introduction of new SYK-like tensor models, which reproduce key features of SYK models in the familiar context of large N field theories.

Most of the literature on tensor models focuses on tensor fields transforming under r independent copies of a symmetry group G, where r is the rank of the tensor (for definiteness, I will focus on r=3 and G=O(N)). The Feynman expansion of such models is indexed by colored stranded diagrams, whose large N scalings are governed by a combinatorial quantity known as the Gurau degree. Tensor models transforming under a single copy of O(N) can be obtained by symmetrization and/or anti-symmetrization of the indices of the tensor. However, such theories turn out to generate a family of stranded diagrams with unbounded Gurau degree, which seems to preclude the construction of an interesting 1/N expansion. Nonetheless, Klebanov and Tarnopolsky recently reported compelling evidence in favour of the conjecture that symmetric tensors can actually support a melonic 1/N expansion, provided that they are also taken to be traceless. In this talk, I will outline the recent complete proof of this conjecture, and will explain why it holds more generally for arbitrary irreducible rank-3 tensor representations. Along the way, I will emphasize the crucial role of the traceless condition. I will conclude by discussing implications and possible generalizations of this result.

New physics has traditionally been expected in the high-pT region at high-energy collider experiments. If new particles are light and weakly-coupled, however, this focus may be completely misguided: light particles are typically highly concentrated within a few mrad of the beam line, allowing sensitive searches with small detectors, and even extremely weakly-coupled particles may be produced in large numbers there.

In this talk I will discuss the recent proposal of FASER, ForwArd Search ExpeRiment at the LHC: a detector placed 480 m downstream of the ATLAS or CMS interaction point (IP) in the very forward region and operated concurrently there.

Even with a small and inexpensive cylindrical detector, of volume ~1 $m^3$, FASER would have a new physics discovery potential in a swath of currently unconstrained parameter-space which is comparable to, and complementary to, much larger proposed experiments. I explore this in the talk for models such as dark photons, dark higgses, axion-like particles, and heavy neutral leptons, and discuss some of the future experimental challenges involved.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1519843500ddcbf452bffff0a1f9a416202b44514a@sns.ias.edu DTSTART:20180228T184500Z DTEND:20180228T200000Z SUMMARY:Physics Group Meeting, "A Tactical Retreat from the BH Information Problem" (Douglas Stanford, Member, School of Natural Sciences, Institute for Advanced Study) DESCRIPTION:In finite entropy systems such as black holes, real-time partition functions do not decay to zero at late times. It is a challenge to derive this non-decaying behavior starting from the path integral over the master fields of a large N theory. I will describe a candidate explanation at varying levels of precision for a variant of the SYK model, for the SYK model itself, and for 2d gravity. Work in progress with Saad and Shenker.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1519844400c0eb0c5583bc95fa859636a4e3306938@sns.ias.edu DTSTART:20180228T190000Z DTEND:20180228T203000Z SUMMARY:High Energy Physics Seminar, "The Tau Lepton as a Tool for SM Physics at CMS" (Isobel Ojalvo, Princeton University) DESCRIPTION:This past year with data collected from the Large Hadron Collider (LHC) using the Compact Muon Solenoid experiment the first observation of the higgs in its decay to tau leptons with a single experiment was announced. Due to its very short lifetime, the tau lepton is normally only possible to detect in its decay to lighter leptons and mesons and in a hadron collider it can be very easily mistaken for a quark or gluon jet. We discuss this exciting result, along with recent advances in tau trigger, reconstruction and identification which made this observation possible as well as prospects for future measurements at the LHC.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1519938000c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20180301T210000Z DTEND:20180301T220000Z SUMMARY:Hamilton Colloquium Series, "Magic Angle Graphene: A New Platform for Strongly Correlated Physics" (Pablo Jarillo-Herrero, MIT) DESCRIPTION:The understanding of strongly correlated quantum matter has challenged physicists for decades. Such difficulties have stimulated new research paradigms, such as ultra-cold atom lattices for simulating quantum materials. In this talk I will present a new platform to investigate strongly correlated physics, based on graphene moiré superlattices. In particular, I will show that when two graphene sheets are twisted by an angle close to the theoretically predicted ‘magic angle’, the resulting flat band structure near the Dirac point gives rise to a strongly correlated electronic system. These flat bands exhibit half-filling insulating phases at zero magnetic field, which we show to be a Mott-like insulator arising from electrons localized in the moiré superlattice. These unique properties of magic-angle twisted bilayer graphene open up a new playground for exotic many-body quantum phases in a 2D platform made of pure carbon and without magnetic field. The easy accessibility of the flat bands, the electrical tunability, and the bandwidth tunability through a twist angle may pave the way towards more exotic correlated systems, such as quantum spin liquids. I will end my talk with an interesting experimental surprise.

LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:152001630016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180302T184500Z DTEND:20180302T200000Z SUMMARY:High Energy Theory Seminar, "$AdS_4/CFT_3$ Beyond Supergravity" (Shai Chester, Princeton University) DESCRIPTION:The paradigmatic example of $AdS_4/CFT_3$ relates M-theory on $AdS_4 x S^7$ to the family of maximally supersymmetric 3d CFTs discovered by Aharony, Bergman, Jafferis, and Maldacena (ABJM). I will focus on the stress tensor four point function for these dual theories. On the CFT side, I will show that all maximally supersymmetric 3d CFTs contain a 1d topological sector that includes only 1/2 and 1/4 BPS operators. I will then use matrix model techniques and the ABJM Lagrangian to compute the OPE coefficients of these BPS operators to all orders in 1/N, where N is the rank of the gauge group. On the $AdS_4$ side, I will use Mellin space and the superconformal Ward identity to express the contribution to the four point function from all higher derivative corrections to $AdS_4$ supergravity, in terms of a set of unknown constants. The leading correction is given by the $R^4$ term in the 11d effective action for M-theory. Using the known coefficient for this term, I will fix the corresponding $AdS_4$ expression, extract the 1/2 and 1/4 BPS OPE coefficients, and compare to the ABJM prediction, finding perfect agreement. This is the first check of $AdS_4/CFT_3$ that goes beyond 11d supergravity.

LOCATION:Jadwin Hall, PCTS Seminar Room 407 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:152027820016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180305T193000Z DTEND:20180305T210000Z SUMMARY:High Energy Theory Seminar, "Going with the Flow: A Solution to the Sign Problem" (Kemal Gokce Basar, University of Illinois at Chicago) DESCRIPTION:I will explore the generalization of the Feynman path integral in quantum field theory to complexified fields, and explain how it can be utilized to tackle the famous "sign problem". The sign problem prevents first principle studies of real-time dynamics and finite density systems via lattice field theory and appears in many different areas in physics. I will discuss both conceptual and computational aspects of this idea and give examples of several interacting quantum field theories where it successfully solves the sign problem.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1520361000a0a055f79333dcef4a7a0c9ef9a70632@sns.ias.edu DTSTART:20180306T183000Z DTEND:20180306T200000Z SUMMARY:Informal High Energy Theory Seminar, "A Positive Sum Rule for the c Anomaly in 4D CFT" (Markus Luty, University of California, Davis) DESCRIPTION: LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:152037000007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20180306T210000Z DTEND:20180306T220000Z SUMMARY:Pheno & Vino Seminar, "Cosmological Signatures of a Mirror Twin Higgs" (Zackaria Chako, University of Maryland) DESCRIPTION:I explore the cosmological signatures associated with the twin baryons, electrons, photons and neutrinos in the Mirror Twin Higgs framework. I consider a scenario in which the twin baryons constitute a subcomponent of dark matter, and the contribution of the twin photon and neutrinos to dark radiation is suppressed due to late time asymmetric reheating, but remains large enough to be detected in future cosmic microwave background (CMB) experiments. I show that this framework leads to distinctive signals in large and small scale structure and the CMB that may allow it to be discovered, and distinguished from other dark sectors.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:152062110016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180309T184500Z DTEND:20180309T200000Z SUMMARY:High Energy Theory Seminar, "Beyond Symmetry: Topological Defect Lines and RG Flows in Two Dimensions" (Shu-Heng Shao, Member, School of Natural Sciences, Institute for Advanced Study) DESCRIPTION:Global symmetries in two dimensions are implemented by topological defect lines (TDLs). For continuous global symmetries, the TDLs are nothing but the Noether charges. However, there are TDLs that are not associated to any global symmetry, and can be thought of as a generalized notion of symmetry. We study the crossing relations of TDLs and use them to constrain renormalization group flows in two dimensions. We show that if certain non-symmetry TDLs are preserved along a flow, then the vacuum cannot be a non-degenerate gapped state. For various massive flows, we bootstrap all the OPE coefficients in the infrared TQFTs from the consideration of TDLs together with modular invariance.LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:152087940016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180312T183000Z DTEND:20180312T193000Z SUMMARY:High Energy Theory Seminar, "Fun with 2-Group Global Symmetries" (Thomas Dumitrescu, Harvard University) DESCRIPTION:

Quantum field theories can have ordinary global symmetries, as well as generalized higher-form symmetries. 2-group symmetries arise when a generalized 1-form symmetry mixes with ordinary global symmetries. I will discuss theories with continuous 2-group symmetries in four and six spacetime dimensions. Continuous 2-group symmetries are characterized by their current algebras, which allow ordinary currents to fuse into the 2-form current associated with the generalized 1-form symmetry. This leads to unconventional Ward identities and ’t Hooft anomalies for 2-group symmetries that constrain the RG flow. The appropriate classical source for the 2-form current is a 2-form background gauge field, which is subject to non-trivial Green-Schwarz shifts under ordinary background gauge transformations. Theories with 2-group symmetry can be constructed by gauging an ordinary flavor symmetry with suitable mixed 't Hooft anomalies. This leads to many simple and explicit examples, some of which I will describe in detail.

LOCATION:Jadwin Hall, PCTS Seminar Room 407 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:152097120007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20180313T200000Z DTEND:20180313T210000Z SUMMARY:Pheno & Vino Seminar, "Exploring the Early Universe with the Higgs" (Patrick Meade, Stony Brook University) DESCRIPTION:I will discuss how we can probe the early universe through studying the properties of the Higgs. I will also demonstrate how the early universe can have a different phase history than is typically assumed. Additionally, I will demonstrate how thermal resummation techniques can be used to study the early universe more accurately.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1521144000c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20180315T200000Z DTEND:20180315T210000Z SUMMARY:Hamilton Colloquium Series, "Neural Circuitry for Navigation in Metric Spaces" (Ila Fiete, University of Texas at Austin) DESCRIPTION:I will review key computational aspects of navigation and describe the brain’s circuits that underlie it. These circuits contain neurons with remarkable responses to spatial variables, including head direction cells, grid cells, and place cells. I’ll describe the likely unifying mechanism for memory and (vector) integration of velocity signals in some of these circuits, across species, including support for the models from quantitative analysis of neural data. I’ll describe how it can be possible to discover, simply from the time-series of spikes in a neural population, the unknown variables a circuit encodes. Finally, given that spatial computations unfold over time, I will review theoretical and experimental efforts to understand the temporal dynamics of navigational computations. I will mention open questions throughout.

LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:152122230016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180316T174500Z DTEND:20180316T190000Z SUMMARY:High Energy Theory Seminar, "Axions Confront High Temperature QCD" (Michael Dine, University of California, Santa Cruz) DESCRIPTION:Recent lattice results on $\theta$ at high temperatures call into question the standard semiclassical analysis of $\theta$-dependence at high temperatures. We examine arguments that there are large uncertainties in these computations, studying both corrections to the Debye mass and infrared sensitivity of the topological susceptibility.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:152148420016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180319T183000Z DTEND:20180319T200000Z SUMMARY:High Energy Theory Seminar, "Tensor Networks as Geometry" (Guifre Vidal, Perimeter Institute) DESCRIPTION:The multiscale entanglement renormalization ansatz (MERA) is a tensor network that can efficiently approximate ground states of critical spin chains --that is, lattice versions of 1+1 CFTs. Its network structure extends in an additional dimension corresponding to renormalization group scale. Accordingly, MERA has has been proposed to be a discrete realization of the AdS/CFT correspondence. While a first proposal speculated that MERA = discrete hyperbolic plane (time slice of AdS3), a second proposal conjectured that MERA = discrete 1+1 de Sitter. In this talk I will attach a geometry to MERA from the perspective of a CFT path integral. Surprisingly, the corresponding metric does not have euclidean nor lorentzian signature, but is instead degenerate. I will also describe how MERA can be modified to represent either the hyperbolic plane or 1+1 de Sitter.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:152182710016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180323T174500Z DTEND:20180323T190000Z SUMMARY:High Energy Theory Seminar, "A Few Uses for Theoretical Physics in Machine Learning" (Dan Roberts, Facebook AI Research) DESCRIPTION: LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:152208900016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180326T183000Z DTEND:20180326T193000Z SUMMARY:High Energy Theory Seminar, "Holographic Duals of 6D SCFTs on Riemann Surfaces" (Ibrahima Bah, Johns Hopkins University) DESCRIPTION:Four-dimensional superconformal field theories can be studied and partially classified by compactifying six-dimensional ones on punctured Riemann surfaces. In this talk we discuss the holographic dual of this set-up and explore how various gravitational sources encode the data associated to the punctures. We also discuss new classes of AdS5 solutions in IIA supergravity that admit all possible solitonic sources.

LOCATION:Jadwin Hall, PCTS Seminar Room 407 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:152218080007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20180327T200000Z DTEND:20180327T210000Z SUMMARY:Pheno & Vino Seminar, "Empirical Determination of the Dark Matter Velocity Distribution" (Lina Necib, MIT) DESCRIPTION:Using the hydrodynamic simulation Eris, as well as various realizations of the Milky Way from the FIRE simulation, we found that the kinematics of dark matter follows closely the kinematics of old metal poor stars. We use this correspondence to obtain the first empirical measurement of the local velocity distribution of dark matter, by first analyzing the Gaia data release coupled with RAVE as well as the ninth release from the Sloan Digital Sky Survey and computing the velocity distribution of metal poor stars. We find that this velocity distribution is peaked at lower velocities than the generally assumed Maxwell Boltzmann distribution, leading to a weakening of direct detection limits at dark matter masses less than 10 GeV by a factor of a few. We also found a few kinematic outliers in the stellar data that might be hints of dark matter substructure.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:152226000016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180328T180000Z DTEND:20180328T190000Z SUMMARY:High Energy Theory Seminar, "A Review of Bifundamental Chern-Simons Theories and the M/N Expansion" (Shiroman Prakash, Dayalbagh Educational Institute, Agra) DESCRIPTION:In this talk we will review some results and conjectures about non-supersymmetric bifundamental *U*(*N*) \times U(*M*) Chern-Simons coupled to matter. It is an apparently unique feature of three-dimensions that one can easily define a variety of non-supersymmetric lines of conformal fixed points via the Chern-Simons kinetic term for a gauge field. An interesting class of conformal fixed points are those based on l *U*(*N*) \times U(*M*) gauge groups coupled to matter transforming as bifundamental representation, which can be thought of as non-supersymmetric generalizations of the ABJ(M) theories. When *M*?*N* these theories are effectively vector models, and are solvable in the large *N* limit. When *M*=*N* the theories are effectively large *N* matrix (or adjoint) models and cannot be solved at strong coupling. Perturbation theory in the parameter *M*/*N* takes one away from the solvable large *N* vector model towards the unsolvable (but more interesting) large *N* matrix model. A holographic dual description, when *M*?*N*, would be a theory of higher spin gauge fields (with extra *U*(*M*) indices), and the parameter *M*/*N* plays the role of a gravitational 't Hooft coupling. We will review some of the few calculations in the *M*/*N* expansion that have been carried out, show how the existence of some non-supersymmetric bifundamental CFT's can be ruled out, and point out various open problems in the field. We may briefly also discuss similar expansions for *U*(*N*)×*O*(*D*)×*U*(*M*)

After recalling how some 4d N=2 gauge theories arise from reductions of 6d N=(2,0) superconformal theories on a Riemann surface, I will discuss two discrete quotients with codimension 2 orbifold singularities. In the first case the orbifold acts by rotations around one plane of the 4d N=2 theory; this is related to a Gukov-Witten surface operator that imposes a monodromy around that plane. We deduce instanton partition functions in the presence of surface operators; interestingly, instantons can fractionalize. In the second case the orbifold acts by reflection on the 4d theory and the Riemann surface.

We learn how boundaries are encoded in the AGT correspondence. We are led to consider 4d N=2 quiver theories where some vector multiplets live on a hemisphere and others on a projective space.

LOCATION:Jadwin Hall, Room A06 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:152269380016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180402T183000Z DTEND:20180402T200000Z SUMMARY:High Energy Theory Seminar, "6d Theories on Circle and Curves" (Cumrun Vafa, Harvard University) DESCRIPTION:In this talk I review new results obtained for SCFT's in 4 and 5 dimensions by compactifying 6 dimensional (1,0) SCFT's on a circle or on Riemann surfaces.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1522958400b269c4a29bfbb0f630895565f3a3a417@sns.ias.edu DTSTART:20180405T200000Z DTEND:20180405T210000Z SUMMARY:Princeton University Department of Physics Donald R. Hamilton Colloquium Series - Added, "The Brascamp-Lieb Inequalities: Structure and algorithms" (Avi Wigderson, Institute for Advanced Study) DESCRIPTION:The celebrated Brascamp-Lieb (BL) inequalities, and their reverse form of Barthe, is a powerful framework which unifies and generalizes many important inequalities in analysis, convex geometry and information theory. I will exemplify BL inequalities, building to the general set-up. I will describe the structural theory that characterizes existence and optimality of these inequalities in terms of their description (called BL-data). But can one efficiently compute existence and optimality from given BL-data? I will describe a recent polynomial time algorithm for these problems. The analysis of this algorithm uses tools from several areas, including invariant theory, quantum information theory, and non-commutative algebra, and resolves some algorithmic problems in these areas as well. I hope to explain some of these connections, and some extensions of this work in the talk as well. Most of this presentation is based on the paper https://arxiv.org/abs/1607.06711.

LOCATION:Jadwin Hall, Room A10 COMMENT:A free lecture open to the public. URL:https://phy.princeton.edu/events/donald-r-hamilton-colloquium-series END:VEVENT BEGIN:VEVENT UID:152303670016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180406T174500Z DTEND:20180406T190000Z SUMMARY:High Energy Theory Seminar, "Topological Terms in Yang-Mills Theory with Time-reversal Symmetry" (Pavel Putrov, Member, School of Natural Sciences, IAS) DESCRIPTION:In my talk I will explicitly describe what topological termspreserving time-reversal symmetry one can introduce in 3+1d Yang-Mills theory. Classification of such terms corresponds to classification of SPTs via cobordisms proposed by Kapustin and Freed-Hopkins. Different topological terms can be detected, for example, by putting the theory on generically non-orientable manifolds. The talk will be mostly based on a joint work with Juven Wang and Meng Guo.LOCATION:IAS Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:15232770003c11a39d4a3e680d3b72ff2b75cab2eb@sns.ias.edu DTSTART:20180409T123000Z DTEND:20180409T220000Z SUMMARY:PCTS Workshop, "Elastic Turbulence" DESCRIPTION:

Elastic turbulence is a chaotic, strongly fluctuating regime of a fluid flow, which, amazingly, occurs at low Reynolds numbers. This phenomenon, observed in polymer solutions, is driven by the strong coupling between the fluid velocity and its elasticity. The statistical features of the flow in this regime have been suggested to be universal, insensitive to the details of the viscoelastic fluid. As such, it may even be relevant as a source of chaos in flows of living organisms on microscopic scales, if the latter exhibit elastic stresses.

The aim of the workshop will be to bring together theoreticians and experimentalists to take stock of the field, and determine what are the outstanding problems and open questions.

We will be selecting a limited number of posters for display during the meeting. If you want to be considered, email the title and abstract for your poster to Anna Frishman, no later than the April 2nd, at **frishman@princeton.edu.**

Eigenstate thermalization hypothesis (ETH) is a phenomena often observed in systems characterized by quantum chaos. In this talk, we study ETH in 2d CFTs with large central charges. In particular, we focus on observables consisting of bilocal "probe" operators O*L*(*x*)O*L*(0). A sharp feature of ETH in this context is the so-called "forbidden" singularities, arising in the thermodynamic limit *c*→∞. We explore their resolutions by finite *c* effects, and analyze the associated non-perturbative phenomena. We also discuss some interesting similarities between the related real-time dynamics and the spectral form factors in both the SYK model and BTZ black holes.

Elastic turbulence is a chaotic, strongly fluctuating regime of a fluid flow, which, amazingly, occurs at low Reynolds numbers. This phenomenon, observed in polymer solutions, is driven by the strong coupling between the fluid velocity and its elasticity. The statistical features of the flow in this regime have been suggested to be universal, insensitive to the details of the viscoelastic fluid. As such, it may even be relevant as a source of chaos in flows of living organisms on microscopic scales, if the latter exhibit elastic stresses.

The aim of the workshop will be to bring together theoreticians and experimentalists to take stock of the field, and determine what are the outstanding problems and open questions.

We will be selecting a limited number of posters for display during the meeting. If you want to be considered, email the title and abstract for your poster to Anna Frishman, no later than the April 2nd, at **frishman@princeton.edu.**

Elastic turbulence is a chaotic, strongly fluctuating regime of a fluid flow, which, amazingly, occurs at low Reynolds numbers. This phenomenon, observed in polymer solutions, is driven by the strong coupling between the fluid velocity and its elasticity. The statistical features of the flow in this regime have been suggested to be universal, insensitive to the details of the viscoelastic fluid. As such, it may even be relevant as a source of chaos in flows of living organisms on microscopic scales, if the latter exhibit elastic stresses.

The aim of the workshop will be to bring together theoreticians and experimentalists to take stock of the field, and determine what are the outstanding problems and open questions.

We will be selecting a limited number of posters for display during the meeting. If you want to be considered, email the title and abstract for your poster to Anna Frishman, no later than the April 2nd, at **frishman@princeton.edu.**

We reduce the dynamics of a nearly-$AdS_2$ spacetime to that of two particles in $AdS_2$. We determine the class of physically meaningful wavefunctions, normalize them, and find the density of states. These can be derived from analytically continuing Euclidean solutions. In Lorentzian signature, the density of states appears in the probability for a particle to tunnel between the asymptotic regions. This tunneling is described by a flux operator, which appears in the decomposition of two-particle functions into single-particle functions. The density of states can also be obtained by normalizing wavefunctions in the classically forbidden region, which we relate to a certain property of SYK microstates. Based on upcoming work with A. Kitaev.

LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:15235776008a9e88d2dcba08eab5665afbe00073ba@sns.ias.edu DTSTART:20180413T000000Z DTEND:20180413T010000Z SUMMARY:Princeton University Department of Physics 43nd Annual Donald R. Hamilton Lecture, "Exploring the Universe with Gravitational Waves: From the Big Bang to Black Holes and Colliding Stars" (Kip Thorne, California Institute of Technology) DESCRIPTION:There are only two types of waves that can propagate across the universe: Electromagnetic waves and gravitational waves. Galileo initiated electromagnetic astronomy 400 years ago, by pointing a telescope at the sky and discovering the moons of Jupiter. The ~1000 physicists and engineers of the LIGO/VIRGO collaboration have recently initiated gravitational astronomy, by observing gravitational waves from black holes that collided 1.3 billion years ago. This discovery has roots at Princeton University, in the 1960s research groups of Robert Dicke and John Wheeler. By the 2030s, physicists and astronomers will have opened four gravitational “windows” onto the universe — the gravitational analogs of optical astronomy, radio astronomy, X-ray astronomy and gamma-ray astronomy — and will be using gravitational waves to observe the big-bang birth of the universe and the first one second of its life.

LOCATION:McDonnell Hall, Room A02 COMMENT:A free lecture open to the public. URL:https://phy.princeton.edu/events/donald-r-hamilton-lecture-kip-thorne-caltech-%E2%80%9Cexploring-universe-gravitational-waves-big-0 END:VEVENT BEGIN:VEVENT UID:152364150016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180413T174500Z DTEND:20180413T184500Z SUMMARY:High Energy Theory Seminar, "Borcherds Kac-Moody Algebras and BPS States in String Theory" (Sarah Harrison, McGill University) DESCRIPTION:Borcherds Kac-Moody (BKM) algebras are a generalization of familiar Kac-Moody algebras with imaginary simple roots. On the one hand, they were invented by Borcherds in his proof of the monstrous moonshine conjectures and have many interesting connections to new moonshines, number theory and the theory of automorphic forms. On the other hand, there is an old conjecture of Harvey and Moore that BPS states in string theory form an algebra that is in some cases a BKM algebra and which is based on certain signatures of BKMs observed in 4d threshold corrections and black hole physics. I will talk about the construction of a new BKM superalgebra which is acted on by the Conway group, and comment on its potential connection to BPS states in string theory.

LOCATION:Jadwin Hall, PCTS Seminar Room 407 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:152390340016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180416T183000Z DTEND:20180416T200000Z SUMMARY:High Energy Theory Seminar, "FZZ Duality and the Black Hole Horizon" (Nissan Itzhaki, Tel Aviv University) DESCRIPTION:We discuss some target space aspects of the FZZ duality both in the Euclidean setup of the cigar geometry and in the SL(2)/U(1) black hole. We argue that the 2D classical SL(2)/U(1) black hole could shed some light on quantum black holes in higher dimensions including large black holes in AdS.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:152416080007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20180419T180000Z DTEND:20180419T190000Z SUMMARY:Pheno & Vino Seminar, "Neutron Stars Chirp about Vacuum Energy" (Csaba Csaki, Cornell University) DESCRIPTION:While the current vacuum energy of the Universe is very small, in our standard cosmological picture it has been much larger at earlier epochs. We try to address the question of what are possible ways to try to experimentally verify the properties of vacuum energy in phases other than the SM vacuum. One promising direction is to look for systems where vacuumenergy constitutes a non-negligible fraction of the total energy, and study the properties of those. Neutron stars could be such systems, and we discuss how to use the recent observation of neutron star mergers to try to learn about the inner core of the neutron star which may be dominated by vacuum energy.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1524168000c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20180419T200000Z DTEND:20180419T210000Z SUMMARY:Hamilton Colloquium Series, "Realizing a Quantum Maxwell’s Demon with Superconducting Circuits" (Kater Murch, Washington University, St. Louis) DESCRIPTION:Thermodynamics is a field of physics that describes quantities such as heat and work and their relationship to entropy and temperature. Originally developed as a theory to optimize the efficiency of heat engines, two extensions of thermodynamics in the last century advanced the theory to the point at which quantum mechanics should be incorporated. First, the role of information in thermodynamics, given by Shannon, Jaynes, and Landauer, makes strong connections between heat, entropy and information. Second, extensions of thermodynamics to the realm of microscopic systems in which fluctuations are significant allow the application of thermodynamics at the level of single trajectories of classical particles. Quantum mechanics requires both of these features as information and fluctuations are central to the behavior of quantum systems. The experimental control over single quantum systems that has been achieved in this century places us in a unique position to extend thermodynamics into the quantum regime. I will describe recent experiments where we harness tools from quantum information processing with superconducting qubits to quantify the role of information in a quantum realization of Maxwell’s demon.

LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:152424630016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180420T174500Z DTEND:20180420T190000Z SUMMARY:High Energy Theory Seminar, "Simplicity in AdS Perturbative Dynamics" (Ellis Ye Yuan, Member, School of Natural Sciences, Institute for Advanced Study) DESCRIPTION:I will make some preliminary investigations to perturbativedynamics in AdS, more precisely the Mellin amplitudes associated to particle scattering, at loop level. With a focus on scalar effective theories, this analysis is fulfilled by introducing an integral operation acting in the Mellin space that triggers a recursive construction fromdiagrams at lower loops to those at higher. This gives rise to a convenient representation for arbitrary scalar diagrams, based on which analytic properties of the amplitudes can be studied systematically. I will provide several simple applications at one and two loops, and further comment on some universal features on the structure of Mellin amplitudes thus observed.LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:152450820016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180423T183000Z DTEND:20180423T200000Z SUMMARY:High Energy Theory Seminar, "From Coxeter Higher-Spin Theories to Strings and Tensor Models" (Mikhail Vasiliev, Lebedev Physical Institute, Moscow) DESCRIPTION:

A new class of higher-spin gauge theories associated with various Coxeter groups is proposed. The emphasize is on the *B**p*--models. The multi-particle *B*2--higher-spin theory is conjectured to be associated with String Theory. *B**p*--higher-spin models with *p*>2 are anticipated to be dual to the rank-*p* boundary tensor sigma-models. *B**p* higher-spin models with *p*≥2 possess two coupling constants responsible for higher-spin interactions in *A**d**S* background and stringy/tensor effects, respectively. Consistency of the holographic interpretation of the boundary matrix-like model in the *B*2-HS model is shown to demand *N*≥4 SUSY, suggesting duality with the *N*=4 SYM upon spontaneous breaking of HS symmetries.

Strong lensing is a sensitive probe of the small-scale density fluctuations in the Universe. We implement a pipeline to model strongly lensed systems using probabilistic cataloging, which is a transdimensional, hierarchical, and Bayesian framework to sample from a metamodel (union of models with different dimensionality) consistent with observed photon count maps. Probabilistic cataloging allows one to robustly characterize modeling covariances within and across lens models with different numbers of subhalos. Unlike traditional cataloging of subhalos, it does not require model subhalos to improve the goodness of fit above the detection threshold. Instead, it allows the exploitation of all information contained in the photon count maps—for instance, when constraining the subhalo mass function. We further show that, by not including these small subhalos in the lens model, fixed-dimensional inference methods can significantly mismodel the data. Using a simulated Hubble Space Telescope data set, we show that the subhalo mass function can be probed even when many subhalos in the sample catalogs are individually below the detection threshold and would be absent in a traditional catalog.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1524678300ddcbf452bffff0a1f9a416202b44514a@sns.ias.edu DTSTART:20180425T174500Z DTEND:20180425T190000Z SUMMARY:Physics Group Meeting, "Discussion on Entanglement Entropy in Gauge Theories" (Jennifer Lin, Member, School of Natural Sciences, Institute for Advanced Study) DESCRIPTION: LOCATION:Bloomberg Hall Physics Library COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1524772800c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20180426T200000Z DTEND:20180426T210000Z SUMMARY:Hamilton Colloquium Series, "The Matter-antimatter Asymmetry of the Universe and the Search for Neutrinoless Double beta Decay" (David Nygren, University of Texas, Arlington) DESCRIPTION:Why is the universe composed only of matter, with negligible anti-matter? Is the neutrino its own anti-particle? These two seemingly disparate questions may be linked through *leptogenesis*–a theory which postulates massive neutrinos that break matter-antimatter asymmetry and could yield the universe we observe, inhabit and explore today. Leptogenesis forces today’s neutrinos to be their own anti-particles with non-zero mass in the range of 50 meV, close to the measured value. The only practical avenue for determining the neutrino nature is the search for an almost unimaginably rare nuclear decay–neutrinoless double beta decay, possible in a few isotopes. I focus on NEXT, an experimental program based on 136Xe, in a high-pressure xenon gas Time Projection Chamber that combines excellent energy resolution and rejection of backgrounds through event topology. Strangely, a biochemistry technique might make success possible. Perhaps an exciting discovery awaits, one that may indicate how the universe chose to keep about one part per billion of matter.

To what extent are deep learning models similar to complex physical systems? I will discuss analogies between aspects of deep learning, glassy systems, and Brownian motion. The results may help us to improve second-order optimization algorithms.LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:15250914003c11a39d4a3e680d3b72ff2b75cab2eb@sns.ias.edu DTSTART:20180430T123000Z DTEND:20180430T220000Z SUMMARY:PCTS Workshop, "Statistical Mechanics Out of Equilibrium" DESCRIPTION: LOCATION:Jadwin Hall, PCTS Seminar Room 407 COMMENT:FREE, but REQUIRED REGISTRATION is limited and available online at http://pcts.princeton.edu/pcts URL:http://wwwphy.princeton.edu/pcts/StatMechanics2018/statmechanics2018.html END:VEVENT BEGIN:VEVENT UID:152511300016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180430T183000Z DTEND:20180430T200000Z SUMMARY:High Energy Theory Seminar, "Probing Binary Black Hole Environments in Hierarchical Triple Systems" (Lisa Randall, Harvard University) DESCRIPTION:

With the recent LIGO results it has been clear that we can learn a lot about the distribution of binary black hole systems. Yet the origin of these black holes is still unknown. Do they come from galactic centers, globular clusters, or from more isolated regions of a galaxy? In this talk I discuss how we can hope to measure eccentricity in LIGO and more direct phase shift and orbital motion measurements in LISA, as a step towards disentangling these possibilities. We show how to analytically approximate eccentricity distributions for systems with slow Kozai-Lidov evolution.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:15251778003c11a39d4a3e680d3b72ff2b75cab2eb@sns.ias.edu DTSTART:20180501T123000Z DTEND:20180501T220000Z SUMMARY:PCTS Workshop, "Statistical Mechanics Out of Equilibrium" DESCRIPTION: LOCATION:Jadwin Hall, PCTS Seminar Room 407 COMMENT:FREE, but REQUIRED REGISTRATION is limited and available online at http://pcts.princeton.edu/pcts URL:http://wwwphy.princeton.edu/pcts/StatMechanics2018/statmechanics2018.html END:VEVENT BEGIN:VEVENT UID:152520480007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20180501T200000Z DTEND:20180501T210000Z SUMMARY:Pheno & Vino Seminar, "Decomposing Strongly Coupled States: Conformal Bases and Hamiltonian Truncation" (Brian Henning, Yale University) DESCRIPTION:Wouldn't it be lovely if we could use the same variational approaches familiar from quantum mechanics to study quantum field theories? We can, of course; the real question is how do we do this efficiently? In this talk I will discuss the recent revival of approximate Hamiltonian diagonalization as a means to numerically study field theories, both of the strong and weak variety, and of Euclidean and Lorentzian signature. Underlying present successes compared to similar attempts last century is a judicious choice of a basis for the unperturbed Hilbert space. One such basis, that has demonstrated promise, is organized according to the conformal symmetry of the UV fixed point.

Motivated by developing ingredients necessary to implement Hamiltonian truncation, we present a new method—using spinors in momentum space—to explicitly construct conformal representations in d=2, 3, and 4 dimensions. This turns out to be interesting in its own right; for example, intriguing structures emerge, notably a U(N) action which generalizes the N-particle U(1)^N action of the little group is found to completely characterize primary operators.

I explore the evolving concepts of space and time in physics.

Today our concepts of spacetime are once again challenged as we struggle to understand quantum gravity, unify the forces of nature, and probe the beginning of the universe.

I discuss some of the ideas that are currently advanced.

LOCATION:McDonnell Hall, Room A-02 COMMENT:Free and Open to the Public URL: END:VEVENT BEGIN:VEVENT UID:1525377600c733b4fafae501f1d0e5f40beb066860@sns.ias.edu DTSTART:20180503T200000Z DTEND:20180503T210000Z SUMMARY:Hamilton Colloquium Series, "The Future of Particle Physics" (David Gross, Kavli Institute for Theoretical Physics at UC-Santa Barbara) DESCRIPTION:The standard model of particle physics is approaching the half-century mark. I shall discuss what we have learned and where we might be headed.

LOCATION:Jadwin Hall, Room A10 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1525705200c0eb0c5583bc95fa859636a4e3306938@sns.ias.edu DTSTART:20180507T150000Z DTEND:20180507T160000Z SUMMARY:High Energy Physics Seminar, "What and why we learn about the Higgs boson properties from the LHC" (Andrei Gritsan, Johns Hopkins University) DESCRIPTION:The Higgs boson discovered six years ago is a fundamentally new state with the spin-parity properties of vacuum. Understanding the vacuum filled with the Higgs field requires deep experimental measurements. Over the past three years during its second run, LHC delivered a number of proton-proton collisions well beyond expectation. We will review some selected results on the Higgs boson properties based on the dataset collected by CMS in this second run of LHC. We will go through the four main topics: Higgs boson couplings to gauge bosons, couplings to fermions, self-couplings, and search for an extended Higgs sector. We will pay particular attention to anomalous couplings in the above interactions and how kinematics in the Higgs boson production and decay can help us to extract maximal information about the Higgs boson properties. Prospects of some of these measurements through the end of run-three and phase-two of LHC will be discussed.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:152571780016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180507T183000Z DTEND:20180507T200000Z SUMMARY:High Energy Theory Seminar, "Chiral Algebras and Twisted Gauge Theories" (Davide Gaiotto, Perimeter Institute) DESCRIPTION: LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1525801500a0a055f79333dcef4a7a0c9ef9a70632@sns.ias.edu DTSTART:20180508T174500Z DTEND:20180508T184500Z SUMMARY:Informal High Energy Theory Seminar, "On Melonic Matrix Models and SYK-like Black Holes" (Frank Ferrari, Universite Libre de Bruxelles) DESCRIPTION:Abstract: I will illustrate three aspects of the new large D limit of matrix models and their applications to black hole physics:

i) Graph theory aspect: I will review the basic properties of the new large D limit of matrix models and provide a simple graph-theoretic argument for its existence, independent of standard tensor model techniques, using the concepts of Tait graphs and Petrie duals.

ii) Phase diagrams: I will outline the interesting phenomena found in the phase diagrams of simple fermionic matrix quantum mechanics/tensor/SYK models at strong coupling, including first and second order phase transitions and quantum critical points. Some of these phase transitions can be argued to provide a quantum mechanical description of the phenomenon of gravitational collapse.

iii) Probe analysis: I will briefly describe how the matrix point of view allows to naturally define models of D-particles probing an SYK-like black hole and discuss the qualitative properties of this class of models, emphasizing the difference between models based on fermionic and on bosonic strings. This approach provides an interesting strategy to study the emerging geometry of melonic/SYK black holes. In particular, it will be explained how a sharply defined notion of horizon emerges naturally.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:152580960007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20180508T200000Z DTEND:20180508T210000Z SUMMARY:Pheno & Vino Seminar, "Testing GR with GWs" (Vitor Cardoso, IST) DESCRIPTION:Two pivotal breakthroughs in physics recently turned respectable centennials: the discovery of the Schwarzschild solution, describing a non-rotating black hole, and Einstein's prediction of gravitational waves. Gravitational waves offer a unique glimpse into the unseen universe, and allow us to test the basic tenets of General Relativity, some of which have been taken for granted without observations: are gravitons massless? Are black holes the simplest possible macroscopic objects? do event horizons and black holes really exist, or is their formation halted by some as-yet unknown mechanism? Do singularities arise in our universe as the outcome of violent collisions? Can gravitational waves carry information about the nature of the elusive dark matter?In this talk, I will describe the science encoded in a gravitational wave signal and what the upcoming years might have in store regarding fundamental physics and gravitational waves.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1525888800c0eb0c5583bc95fa859636a4e3306938@sns.ias.edu DTSTART:20180509T180000Z DTEND:20180509T190000Z SUMMARY:High Energy Physics Seminar, "First Measurement of Monoenergetic Muon Neutrino Charged Current Interactions" (Rory Fitzpatrick, University of Michigan) DESCRIPTION:The NuMI beam absorber at Fermilab provides an intense source of 236 MeV muon neutrinos originating from kaon decay at rest that are observed by the MiniBooNE detector. The kaon-decay-at-rest (KDAR) neutrino represents a standard candle for studying neutrino-nucleus interactions, cross sections, and energy reconstruction in the hundreds of MeV region and has also been proposed for use in a number of precision physics measurements. I will present recent results from MiniBooNE which report the first known-energy, weak-interaction-only probe of the nucleus to yield a measurement of neutrino-nucleus energy transfer, a parameter traditionally only accessible via electron scattering.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:15263010003c11a39d4a3e680d3b72ff2b75cab2eb@sns.ias.edu DTSTART:20180514T123000Z DTEND:20180514T220000Z SUMMARY:PCTS Workshop, "Bridging Mathematical Optimization, Information Theory, and Data Science" DESCRIPTION:Recent years have witnessed a flurry of exciting new developments and activities in the intersection of optimization theory, information theory, and mathematical data science. For instance, optimization theory inspires algorithmic breakthroughs in machine learning and reinforcement learning; information theory offers powerful tools for understanding the fundamental limits in numerous data science applications; and the growing popularity of data science and statistical learning in turn provides new data-driven perspectives to optimization paradigms and enriches the toolbox of information theory.

The goal of this workshop is to bring together participants from multiple communities including mathematical optimization, information theory, statistics, and machine learning in order to conduct in-depth discussion and motivate interdisciplinary collaboration.

This workshop is supported in part by Princeton Center for Statistics and Machine Learning (CSML); Department of Electrical Engineering; and Department of Operations Research and Financial Engineering (ORFE).

Recent years have witnessed a flurry of exciting new developments and activities in the intersection of optimization theory, information theory, and mathematical data science. For instance, optimization theory inspires algorithmic breakthroughs in machine learning and reinforcement learning; information theory offers powerful tools for understanding the fundamental limits in numerous data science applications; and the growing popularity of data science and statistical learning in turn provides new data-driven perspectives to optimization paradigms and enriches the toolbox of information theory.

The goal of this workshop is to bring together participants from multiple communities including mathematical optimization, information theory, statistics, and machine learning in order to conduct in-depth discussion and motivate interdisciplinary collaboration.

This workshop is supported in part by Princeton Center for Statistics and Machine Learning (CSML); Department of Electrical Engineering; and Department of Operations Research and Financial Engineering (ORFE).

The missing mass problem has been with us for decades, but laboratory detection of hypothesized dark matter candidates remains elusive. While some lines of evidence seem to absolutely require the existence of some novel form of non-baryonic dark matter (e.g., the cosmic microwave background), others auger against it (e.g., the dynamics of gravitationally bound systems) and suggest the even more radical possibility that it is our understanding of dynamics that remains wanting. I will focus on issues we still don't understand where progress may require new ideas.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:15264738003c11a39d4a3e680d3b72ff2b75cab2eb@sns.ias.edu DTSTART:20180516T123000Z DTEND:20180516T220000Z SUMMARY:PCTS Workshop, "Bridging Mathematical Optimization, Information Theory, and Data Science" DESCRIPTION:Recent years have witnessed a flurry of exciting new developments and activities in the intersection of optimization theory, information theory, and mathematical data science. For instance, optimization theory inspires algorithmic breakthroughs in machine learning and reinforcement learning; information theory offers powerful tools for understanding the fundamental limits in numerous data science applications; and the growing popularity of data science and statistical learning in turn provides new data-driven perspectives to optimization paradigms and enriches the toolbox of information theory.

The goal of this workshop is to bring together participants from multiple communities including mathematical optimization, information theory, statistics, and machine learning in order to conduct in-depth discussion and motivate interdisciplinary collaboration.

This workshop is supported in part by Princeton Center for Statistics and Machine Learning (CSML); Department of Electrical Engineering; and Department of Operations Research and Financial Engineering (ORFE).

I discuss a new family of four-dimensional CFTs, recently proposed by O.Gurdogan and myself, emerging as a double scaling limit of weakly coupled and strongly gamma-twisted N=4 SYM theory. These non-supersymmetric and non-unitary CFTs inherit the planar integrability of N=4 SYM and present a unique opportunity of non-perturbative study of four-dimensional conformal physics. Important physical quantities are dominated by a limited set of "chiral" Feynman graphs, such as "fishnet" graphs for the simplest, bi-scalar model. I present the results of exact calculation of some of these quantities, such as anomalous dimensions of local operators, some 3- and 4-point correlation functions and scattering amplitudes, by means of quantum spin chain techniques or the quantum spectral curve (QSC) approach originally proposed for N=4 SYM. The bi-scalar theory appears to be a remarkable "generator" of large families of integrable, i.e. computable multi-loop Feynman graphs.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1527098400c0eb0c5583bc95fa859636a4e3306938@sns.ias.edu DTSTART:20180523T180000Z DTEND:20180523T193000Z SUMMARY:High Energy Physics Seminar, "K+ to pi+ nu nubar - First Result from NA62 Experiment" (Bob Velghe, TRIUMF) DESCRIPTION:The K+ to pi+ nu nubar decay has been attracting interest for many decades. The accurate measurement of its branching ratio is a powerful test of the Standard Model (SM) and could reveal effects beyond the SM. As the decay occurs at the level of 1 in 10 billion kaon disintegration, many experimental challenges have to be overcome. The CERN NA62 experiment uses a novel kaon decay-in-flight technique to observe K+ to pi+ nu nubar. The analysis of the 2016 data set was used to establish the method by allowing us to reach the $10^-10$ single event sensitivity. The preliminary NA62 result on K+ to pi+ nu nubar from the analysis of the full 2016 data set will be presented.

LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1527788700a0a055f79333dcef4a7a0c9ef9a70632@sns.ias.edu DTSTART:20180531T174500Z DTEND:20180531T190000Z SUMMARY:Informal High Energy Theory Seminar, "Scattering Amplitudes from Intersection Theory" (Sebastian Mizera, Perimeter Institute) DESCRIPTION: LOCATION:IAS, Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1528117200c3f67ac4051decfc3f0121724956628d@sns.ias.edu DTSTART:20180604T130000Z DTEND:20180604T210000Z SUMMARY:School of Math Workshop, "Conference on Optimization, Complexity and Invariant Theory" DESCRIPTION:This workshop aims to explore connections between complexity and optimization with algebra and analysis, which have emerged from the works on operator scaling. The hope is to inform participants from different communities of both basic tools and new developments, and set out new challenges and directions for this exciting interdisciplinary research.

Some of the topics and notions that will be explored include:**Optimization**: Alternate minimization. Scaling algorithms. Gradient methods for geodesic convexity. Brascamp-Lieb polytopes. Entropy optimality.**Invariant Theory**: Linear group actions, and degree bounds on invariant rings. Nullcone and orbit closure intersection problems. Moment polytopes. Non-commutative duality. Algorithms avoiding Grobner bases.**Computational complexity**: Commutative and non-commutative arithmetic circuits. Symbolic matrices. Polynomial identity testing. Tensor rank. Geometric complexity theory.**Quantum Information Theory**: Completely positive operators. Quantum distillation. Entanglement polytopes.

Since the discovery of Higgs, particle physics is now face a transition. What is the next step is the major questions to our field. I will discuss an initiative from China: Circular electron-positron Collider and its design and R&D progress. In addition, I will cover projects in China on cosmic-ray physics, neutrino physics, and science program in space.

LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:1528203600c3f67ac4051decfc3f0121724956628d@sns.ias.edu DTSTART:20180605T130000Z DTEND:20180605T210000Z SUMMARY:School of Math Workshop, "Conference on Optimization, Complexity and Invariant Theory" DESCRIPTION:This workshop aims to explore connections between complexity and optimization with algebra and analysis, which have emerged from the works on operator scaling. The hope is to inform participants from different communities of both basic tools and new developments, and set out new challenges and directions for this exciting interdisciplinary research.

Some of the topics and notions that will be explored include:**Optimization**: Alternate minimization. Scaling algorithms. Gradient methods for geodesic convexity. Brascamp-Lieb polytopes. Entropy optimality.**Invariant Theory**: Linear group actions, and degree bounds on invariant rings. Nullcone and orbit closure intersection problems. Moment polytopes. Non-commutative duality. Algorithms avoiding Grobner bases.**Computational complexity**: Commutative and non-commutative arithmetic circuits. Symbolic matrices. Polynomial identity testing. Tensor rank. Geometric complexity theory.**Quantum Information Theory**: Completely positive operators. Quantum distillation. Entanglement polytopes.

This workshop aims to explore connections between complexity and optimization with algebra and analysis, which have emerged from the works on operator scaling. The hope is to inform participants from different communities of both basic tools and new developments, and set out new challenges and directions for this exciting interdisciplinary research.

Some of the topics and notions that will be explored include:**Optimization**: Alternate minimization. Scaling algorithms. Gradient methods for geodesic convexity. Brascamp-Lieb polytopes. Entropy optimality.**Invariant Theory**: Linear group actions, and degree bounds on invariant rings. Nullcone and orbit closure intersection problems. Moment polytopes. Non-commutative duality. Algorithms avoiding Grobner bases.**Computational complexity**: Commutative and non-commutative arithmetic circuits. Symbolic matrices. Polynomial identity testing. Tensor rank. Geometric complexity theory.**Quantum Information Theory**: Completely positive operators. Quantum distillation. Entanglement polytopes.

**Optimization**: Alternate minimization. Scaling algorithms. Gradient methods for geodesic convexity. Brascamp-Lieb polytopes. Entropy optimality.**Invariant Theory**: Linear group actions, and degree bounds on invariant rings. Nullcone and orbit closure intersection problems. Moment polytopes. Non-commutative duality. Algorithms avoiding Grobner bases.**Computational complexity**: Commutative and non-commutative arithmetic circuits. Symbolic matrices. Polynomial identity testing. Tensor rank. Geometric complexity theory.**Quantum Information Theory**: Completely positive operators. Quantum distillation. Entanglement polytopes.

**Optimization**: Alternate minimization. Scaling algorithms. Gradient methods for geodesic convexity. Brascamp-Lieb polytopes. Entropy optimality.**Invariant Theory**: Linear group actions, and degree bounds on invariant rings. Nullcone and orbit closure intersection problems. Moment polytopes. Non-commutative duality. Algorithms avoiding Grobner bases.**Computational complexity**: Commutative and non-commutative arithmetic circuits. Symbolic matrices. Polynomial identity testing. Tensor rank. Geometric complexity theory.**Quantum Information Theory**: Completely positive operators. Quantum distillation. Entanglement polytopes.

In this talk I present theoretical evidence, based on non-perturbative semi-classical quantization techniques, that what appears as the annihilation of Positronium (Ps) may in reality be just another electromagnetic transition from the hydrogenic pseudo-ground state of Ps to a true quantum-mechanical ground state near zero energy, caused by the magnetic interactions of the particles. This ground state cannot be found by perturbing around the hydrogenic pseudo-ground state using the usual Feynman diagram techniques. Once in this tightly bound near-0 energy ground state, Ps would behave effectively like an ultralight neutral spin-0 boson --- the very type of particle currently thought to be the most likely explanation for the mysterious dark matter in the universe.

LOCATION:Jadwin Hall, Room 343 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:153755190016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180921T174500Z DTEND:20180921T190000Z SUMMARY:High Energy Theory Seminar, "TBA" (TBA, TBA) DESCRIPTION: LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:153781380016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180924T183000Z DTEND:20180924T200000Z SUMMARY:High Energy Theory Seminar, "TBA" (TBA, TBA) DESCRIPTION: LOCATION:Jadwin Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:153790560007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20180925T200000Z DTEND:20180925T210000Z SUMMARY:Pheno & Vino Seminar, "TBA" (Cora Dvorkin, Harvard University) DESCRIPTION: LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:153815670016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20180928T174500Z DTEND:20180928T190000Z SUMMARY:High Energy Theory Seminar, "TBA" (TBA, TBA) DESCRIPTION: LOCATION:Jadwin Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:153841860016edf9d904301463b51986b288d83b0b@sns.ias.edu DTSTART:20181001T183000Z DTEND:20181001T200000Z SUMMARY:High Energy Theory Seminar, "TBA" (William Donnelly, Perimeter Institute) DESCRIPTION: LOCATION:Bloomberg Lecture Hall COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:153851040007265ec0b683dc73f6f9a87b1b1f8ec7@sns.ias.edu DTSTART:20181002T200000Z DTEND:20181002T210000Z SUMMARY:Pheno & Vino Seminar, "TBA" (Marilena Loverde, Stony Brook University) DESCRIPTION: LOCATION:Jadwin Hall, Room 303 COMMENT: URL: END:VEVENT BEGIN:VEVENT UID:15385716003c11a39d4a3e680d3b72ff2b75cab2eb@sns.ias.edu DTSTART:20181003T130000Z DTEND:20181003T210000Z SUMMARY:PCTS Workshop, "Critical Phenomena in Statistical Mechanics and Quantum Field Theory" DESCRIPTION:Program Organizers: Michael Aizenman, Igor Klebanov and Silviu Pufu

This is a satellite event in association with XIX International Congress on Mathematical Physics.

For a list of speakers, click here.

Program Organizers: Michael Aizenman, Igor Klebanov and Silviu Pufu

This is a satellite event in association with XIX International Congress on Mathematical Physics.

For a list of speakers, click here.

Program Organizers: Michael Aizenman, Igor Klebanov and Silviu Pufu

This is a satellite event in association with XIX International Congress on Mathematical Physics.

For a list of speakers, click here.