# Physics Events

• Monday, February 19, 2018
High Energy Theory Seminar
“Holographic Entanglement and Poincare Blocks in Three-Dimensional Flat Space”

Location: Jadwin Hall, PCTS Seminar Room 407
Time: 2:30 PM
Speaker(s): 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.

• Tuesday, February 20, 2018
Special CM Seminar
“The Topology and Quantum Criticality in 1+1D”

Location: Jadwin Hall, PCTS Seminar Room 407
Time: 2:00 PM
Speaker(s): 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.

• Tuesday, February 20, 2018
Pheno & Vino Seminar
“The Strong CP Problem and UV Instantons”

Time: 4:00 PM
Speaker(s): 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.

• Thursday, February 22, 2018
Hamilton Colloquium Series
“Motifs in Morphogenesis”

Time: 4:00 PM

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.

• Friday, February 23, 2018
High Energy Theory Seminar
“Splittability and Noether's Theorem in Quantum Field Theory”

Location: Bloomberg Lecture Hall
Time: 1:45 PM
Speaker(s): 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.

• Monday, February 26, 2018
High Energy Theory Seminar
“TBA”

Location: Jadwin Hall, PCTS Seminar Room 407
Time: 2:30 PM
Speaker(s): Sylvain Carrozza, Perimeter Institute

• Tuesday, February 27, 2018
Pheno & Vino Seminar
“TBA”

Time: 4:00 PM
Speaker(s): Iftah Galon, Rutgers University

• Wednesday, February 28, 2018
High Energy Physics Seminar
“The Tau Lepton as a Tool for SM Physics at CMS”

Time: 2:00 PM
Speaker(s): 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.

• Thursday, March 1, 2018
Hamilton Colloquium Series
“TBA”

Location: TBA
Time: 4:00 PM
Speaker(s): Pablo Jarillo-Herrero, MIT

• Friday, March 2, 2018
High Energy Theory Seminar
“TBA”

Location: Jadwin Hall, PCTS Seminar Room 407
Time: 1:45 PM
Speaker(s): Shai Chester, Princeton University

• Monday, March 5, 2018
High Energy Theory Seminar
“Going with the Flow: A Solution to the Sign Problem”

Location: Bloomberg Lecture Hall
Time: 2:30 PM
Speaker(s): 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.

• Tuesday, March 6, 2018
Pheno & Vino Seminar
“TBA”

Time: 4:00 PM
Speaker(s): Zackaria Chako, University of Maryland

• Friday, March 9, 2018
High Energy Theory Seminar
“TBA”

Location: Bloomberg Lecture Hall
Time: 1:45 PM
Speaker(s): TBA, TBA

• Monday, March 12, 2018
High Energy Theory Seminar
“TBA”

Location: Jadwin Hall, PCTS Seminar Room 407
Time: 2:30 PM
Speaker(s): Thomas Dumitrescu, Harvard University

• Tuesday, March 13, 2018
Pheno & Vino Seminar
“TBA”

Time: 4:00 PM
Speaker(s): Patrick Meade, Stony Brook University

• Friday, March 16, 2018
High Energy Theory Seminar
“TBA”

Location: Bloomberg Lecture Hall
Time: 1:45 PM
Speaker(s): TBA, TBA

• Monday, March 19, 2018
High Energy Theory Seminar
“Tensor Networks as Geometry”

Location: Bloomberg Lecture Hall
Time: 2:30 PM
Speaker(s): 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.

• Tuesday, March 20, 2018
Pheno & Vino Seminar
“TBA”

Time: 4:00 PM
Speaker(s): Patrick Meade, Stony Brook University

• Friday, March 23, 2018
High Energy Theory Seminar
“TBA”

Location: Bloomberg Lecture Hall
Time: 1:45 PM
Speaker(s): TBA, TBA

• Monday, March 26, 2018
High Energy Theory Seminar
“TBA”

Location: Jadwin Hall, PCTS Seminar Room 407
Time: 2:30 PM
Speaker(s): Ibrahima Bah, Johns Hopkins University

• Tuesday, March 27, 2018
Pheno & Vino Seminar
“TBA”

Time: 4:00 PM
Speaker(s): Gustavo Marquis Tavares, Stanford University

• Friday, March 30, 2018
High Energy Theory Seminar
“TBA”

Time: 1:45 PM
Speaker(s): Bruno Le Floch, Princeton University

• Monday, April 2, 2018
High Energy Theory Seminar
“TBA”

Location: Bloomberg Lecture Hall
Time: 2:30 PM
Speaker(s): Cumrun Vafa, Harvard University

• Friday, April 6, 2018
High Energy Theory Seminar
“TBA”

Location: Bloomberg Lecture Hall
Time: 1:45 PM
Speaker(s): TBA, TBA

• Monday, April 9, 2018
PCTS Workshop
“Elastic Turbulence”

Location: Jadwin Hall, PCTS Seminar Room, Room 407
Time: 8:30 AM
Note: FREE, but REQUIRED REGISTRATION is limited and available online: http://wwwphy.princeton.edu/pcts/Turbulence2018/Turbulence2018.html

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.

• Tuesday, April 10, 2018
PCTS Workshop
“Elastic Turbulence”

Location: Jadwin Hall, PCTS Seminar Room, Room 407
Time: 8:30 AM
Note: FREE, but REQUIRED REGISTRATION is limited and available online: http://wwwphy.princeton.edu/pcts/Turbulence2018/Turbulence2018.html

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.

• Wednesday, April 11, 2018
PCTS Workshop
“Elastic Turbulence”

Location: Jadwin Hall, PCTS Seminar Room, Room 407
Time: 8:30 AM
Note: FREE, but REQUIRED REGISTRATION is limited and available online: http://wwwphy.princeton.edu/pcts/Turbulence2018/Turbulence2018.html

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.

• Thursday, April 12, 2018
Donald R. Hamilton Lecture
“TBA”

Location: McDonnell Hall, A02 Auditorium
Time: 8:00 PM
Speaker(s): Kip Thorne, Richard P. Feynman Professor of Theoretical Physics, Emeritus, California Institute of Technology (Caltech) and Winner of the 2017 Nobel Prize in Physics

• Friday, April 13, 2018
High Energy Theory Seminar
“TBA”

Location: Jadwin Hall, PCTS Seminar Room 407
Time: 1:45 PM
Speaker(s): Sarah Harrison, McGill University

• Monday, April 16, 2018
High Energy Theory Seminar
“TBA”

Location: Bloomberg Lecture Hall
Time: 2:30 PM
Speaker(s): Nissan Itzhaki, Tel Aviv University

• Friday, April 20, 2018
High Energy Theory Seminar
“TBA”

Location: Bloomberg Lecture Hall
Time: 1:45 PM
Speaker(s): TBA, TBA

• Monday, April 30, 2018
High Energy Theory Seminar
“TBA”

Location: Bloomberg Lecture Hall
Time: 2:30 PM
Speaker(s): TBA, TBA

• Friday, May 4, 2018
High Energy Theory Seminar
“TBA”

Location: Bloomberg Lecture Hall
Time: 1:45 PM
Speaker(s): TBA, TBA

• Monday, May 7, 2018
High Energy Theory Seminar
“TBA”

Location: Bloomberg Lecture Hall
Time: 2:30 PM
Speaker(s): TBA, TBA