Events Archive

HET Seminar | Alexei Kitaev, Caltech | “Topological Quantum Phases” | Bloomberg Lecture Hall
Fri, Dec 13, 2019, 1:45 pm1:45 pm

 I will discuss topological classification of gapped many-body Hamiltonians and their ground states in dimension d. In general, the problem is too hard as it includes diverse phenomena such as degenerate ground states on the torus, anyons, and fractons. There is, however, hope to fully understand short-range entangled, or "invertible" systems,…

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Physics Group Meeting | Sridip Pal, IAS | "Towards optimal asymptotic spectral gap in 2D unitary GFT" | Bloomberg Hall Physics Library
Wed, Dec 11, 2019, 1:45 pm1:45 pm

We will prove a conjecture [1] on upper bound of asymptotic gap in dimension in unitary compact 2D CFT, proving it to be 1 using a "extremal" function [2]. The notion of asymptotic gap can be generalized to (h, \bar{h}) plane [3]. We will discuss how the extremal function used in [2] can be put into a bigger (natural) framework of an extremal…

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HET Seminar - Radu Roiban - Pennsylvania State University
Mon, Nov 25, 2019, 2:30 pm2:30 pm
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A free lecture open to the public.
HET Seminar | Edgar Shaghoulian, Cornell | "Integrable deformations in quantum mechanics, T-Tbar, and SYK" | Jadwin A06
Wed, Nov 20, 2019, 4:00 pm4:00 pm

The Wilsonian paradigm suggests universality of quantum field theory in the infrared. Interestingly, it also suggests universality of quantum mechanics (d=1 quantum field theory) in the ultraviolet. This suggests a study of the landscape of the infrared and the robustness of the ultraviolet. I will introduce and…

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A free lecture open to the public.
HET Seminar | Theo Johnson-Freyd, Perimeter Institute | “TMF and SQFT” | Bloomberg Lecture Hall
Mon, Nov 18, 2019, 2:30 pm2:30 pm

I will describe my work, all joint with D. Gaiotto and some also joint with E. Witten, to understand the homotopy type of the space of (1+1)d N=(0,1) SQFTs --- what a condensed matter theorist would call "phases" of SQFTs. Our motivating hypothesis (due in large part to Stolz and Teichner) is that this space models the spectrum called …

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A free lecture open to the public.
High Energy Theory | Joao Penedones, EPFL | "S-matrix Bootstrap for Effective Field Theories"
Mon, Nov 11, 2019, 2:30 pm2:30 pm

I will explain how the S-matrix Bootstrap for massless particles can be used to constrain the space of Effective Field Theories (EFT). In particular, I will discuss the S-matrix bootstrap for massless particles in unitary, relativistic two dimensional quantum field theories. In the context of flux tube physics, this…

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A free lecture open to the public.
Physics Group Meeting | "Title to be announced." | Bloomberg Hall Physics Library
Mon, Nov 11, 2019, 1:45 pm1:45 pm
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HET Seminar | Callum Jones, U of Michigan | "Born-Infeld Electrodynamics at One-Loop” | Jadwin A06
Tue, Nov 5, 2019, 3:00 pm3:00 pm

The Born-Infeld model is an effective field theory of central importance describing the low-energy dynamics of massless gauge bosons on the world-volume of D-branes. Though it is in many ways an exceptional model of nonlinear electrodynamics, several aspects of the physics of the Born-Infeld model remain mysterious…

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A free lecture open to the public.
High Energy Theory | Jacobus Verbaarschot, Stony Brook | "Chaotic and Thermodynamic Properties of two Coupled Sachdev-Ye-Kitaev Models" | PCTS Seminar Room 407
Mon, Nov 4, 2019, 2:30 pm2:30 pm

The SYK Model was originally introduced as a random matrix model for the nuclear interaction  that also describes the exponential rise of the spectral density known as  the Bethe formula. Exactly this behavior is the hallmark of the Schwarzian action, the low energy limit of the SYK model, which is the main reason for the excitement this model…

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A free lecture open to the public.
Physics Group Meeting | Nafiz Ishtiaque, IAS | “Topological Holography” | Bloomberg Hall Physics Library
Wed, Oct 30, 2019, 1:45 pm1:45 pm

We consider supersymmetric twist and omega deformation of a type IIB brane setup involving N D3 and K D5 branes. In the large N limit, this leads to a holographic duality between two topological/holomorphic theories. We compute certain operator algebras from both sides of this topological holographic duality and…

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HET Seminar | Tom Hartman, Cornell University | "Dynamical Constraints on RG Flows and Cosmology” | Bloomberg Lecture Hall
Mon, Oct 28, 2019, 2:30 pm2:30 pm

I will discuss time-dependent probes of the renormalization group, and derive new constraints that govern the spread of local operators in holographic theories. The same methods lead to sum rules for inflationary correlators, relating observables, like the speed of sound during inflation, to properties of the UV…

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A free lecture open to the public.
Physics Group Meeting at IAS | Robert Penna, IAS | “The Geroch Group” | Bloomberg Hall Physics Library
Wed, Oct 23, 2019, 1:45 pm1:45 pm

We review some infinite dimensional symmetries that appear indimensionally reduced classical general relativity.  Reducing from d=4to d=2 gives a two dimensional nonlinear sigma model with an infinitedimensional affine Kac-Moody symmetry called the Geroch group.Further reducing to d=1 (along a null Kill vector)…

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Physics Group Meeting at IAS | Robert Penna, IAS | “The Geroch Group” | Bloomberg Hall Physics Library
Wed, Oct 23, 2019, 1:45 pm1:45 pm

We review some infinite dimensional symmetries that appear indimensionally reduced classical general relativity.  Reducing from d=4to d=2 gives a two dimensional nonlinear sigma model with an infinitedimensional affine Kac-Moody symmetry called the Geroch group.Further reducing to d=1 (along a null Kill vector)…

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HET Seminar | Bruno Balthazar, Harvard | "ZZ Instantons and the Non-Perturbative Dual of c=1 String Theory" | Jadwin A07
Mon, Oct 21, 2019, 2:30 pm2:30 pm

 

We study the effect of ZZ instantons in c = 1 string theory, and demonstrate that they give rise to non-perturbative corrections to closed string scattering amplitudes that do not saturate unitarity within the closed string sector. Beyond the leading non-perturbative order,…

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A free lecture open to the public.
High Energy Theory | Sabrina Gonzalez Pasterski - Princeton | "4D Scattering as 2D Correlators"
Fri, Oct 18, 2019, 1:45 pm1:45 pm

The asymptotic symmetry algebra of asymptotically flat spacetimes implies an infinity of conserved charges for 4D scattering which can be neatly recast as 2D conformal Ward identities. We cover recent progress on the proposed 4D/2D dictionary starting from the conformally soft modes that appear as currents and…

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A free lecture open to the public.
Physics Group Meeting at IAS | Baurzhan Mukhametzhanov, IAS | “Matrix Models and Minimal Liouville Gravity” | Bloomberg Lecture Hall
Wed, Oct 16, 2019, 1:45 pm1:45 pm

I will review some old ideas about the duality between matrix models and Liouville theory coupled to a  (p,q) minimal model. In this approach t'Hooft diagrams of the matrix model are thought of as a discretization of a 2d surface. Fine-tuning of the coupling constant leads to divergence of the perturbative expansion…

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HET Seminar | Geoff Penington | Stanford University | “Entanglement Wedge Reconstruction and the Information Paradox” | Bloomberg Lecture Hall
Mon, Oct 14, 2019, 2:30 pm2:30 pm

When absorbing boundary conditions are used to evaporate a black hole in AdS/CFT, we show that there is a phase transition in the location of the quantum Ryu-Takayanagi surface, at precisely the Page time. The new RT surface lies slightly inside the event horizon, at an infalling time approximately one scrambling…

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A free lecture open to the public.
High Energy Theory - "dS thermodynamics from bulk and horizon characters" Zimo Sun - Columbia
Fri, Oct 11, 2019, 1:45 pm1:45 pm

In this talk, I will discuss the idea that the exact one-loop free energy of the static patch of D-dimensional de Sitter space can be computed as a simple integral transform of an SO(1;D) bulk character corrected by an SO(1; D-2) edge character, for fields of arbitrary mass and spin. The bulk character captures the…

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A free lecture open to the public.
Physics Group Meeting @ IAS | Daniel Kapec, IAS | “Black Hole Images and the Photon Ring” | Bloomberg Hall Physics Library
Wed, Oct 9, 2019, 1:45 pm1:45 pm

The EHT Collaboration has recently published images of the supermassive black hole in M87. The images are dominated by a bright ring-like structure with an angular brightness asymmetry. While the diameter of this ring is resolved by the EHT, its thickness and detailed substructure are not. General relativity…

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HET Seminar | Andrea Dei, ETH Zurich | "Three-point functions in AdS3/CFT2 holography." | Jadwin A06
Tue, Oct 8, 2019, 3:00 pm3:00 pm

String theory on AdS3xS3xT4 with one unit of NSNS flux has been recently argued to be dual to the symmetric product orbifold of T^4. The duality has been extended to the case of generic NSNS background flux. I will consider the bosonic version of this duality and show how to match null-vector constraints on three…

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A free lecture open to the public.