Events Archive

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)…

Speaker
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.
High Energy Theory - "Supersymmmetric Lifshitz Field Theories", Avia Raviv-Moshe - Tel-Aviv
Mon, Oct 7, 2019, 2:30 pm2:30 pm

Abstract: Lifshitz scaling is an anisotropic scaling where time and space scale differently. Quantum field theories that exhibit Lifshitz scale symmetry provide a framework for studying low energy systems with an emergent dynamic scaling such as quantum critical points. Introducing supersymmetry to the Lifshitz algebra leads to a rich structure…

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A free lecture open to the public.
HET Seminar | Jorge Santos, Cambridge | “Hawking Radiation at Strong Coupling: A Case for Braneworld Black Holes” | Bloomberg Hall Physics Library
Wed, Oct 2, 2019, 1:45 pm1:45 pm

Gauge/gravity duality relates certain strongly coupled CFTs with large effective central charge to semi-classical gravitational theories with AdS asymptotics. I will describe recent progress in understanding gravity duals for CFTs on non-trivial spacetimes with black hole horizons. Such gravity methods provide…

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High Energy Theory - "Probing nonperturbative structures in gravity with SYK model" Mikhail Khramtsov - Steklov Institute | Jadwin A06
Tue, Oct 1, 2019, 2:00 pm2:00 pm

My talk is devoted to studies of large N saddle point structures in the SYK model beyond the commonly used approximations, in particular the replica-diagonal assumption and the conformal limit. We will discuss new solutions of the saddle point equations in the SYK and their role in physics of the model and in the gravity dual description. We…

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A free lecture open to the public.
HET Seminar - Andrew Turner - Massachusetts Institute of Technology
Mon, Sep 30, 2019, 2:30 pm2:30 pm
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A free lecture open to the public.
HET Seminar | Sebastian Mizera, IAS | “Aspects of Scattering Amplitudes and Moduli Space Localization” | Bloomberg Lecture Hall
Fri, Sep 27, 2019, 1:45 pm1:45 pm

We review a recent geometric formulation of the tree-level S-matrix of various quantum field theories, including gauge and gravity theories, in terms of intersection numbers of twisted cohomology groups on the moduli space of genus-zero curves with marked points. Scattering amplitudes are computed in terms of…

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Physics Group Meeting | Joonho Kim, IAS | "Cardy Formula and AdS Black Holes” | Bloomberg Hall Physics Library
Wed, Sep 25, 2019, 1:45 pm1:45 pm

I will discuss recent progress about the Cardy-like asymptotics of 4d supersymmetric index on S^3, also known as superconformal index. The main observation is that Bose-Fermi cancellation that trivializes the asymptotic expression of the index can be obstructed by complexifying chemical potentials. Applied to N=4…

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High Energy Theory - “Walking, weakly first order phase transitions and complex CFTs” - Bernardo Zan - Princeton
Mon, Sep 23, 2019, 2:30 pm2:30 pm

I will discuss walking behavior in gauge theories and weakly first order phase transition in statistical models. Despite being phenomena appearing in very different physical systems, they both show a region of approximate scale invariance. They can be understood as a RG flow passing between two fixed points living at complex couplings, which we…

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A free lecture open to the public.
High Energy Theory - The non-local non-linear sigma model - Christian Jepsen - Princeton
Fri, Sep 20, 2019, 1:45 pm1:45 pm

In this talk, based on work with S. Gubser, Z. Ji, B. Trundy, and A. Yarom, I present a scalar theory described by an action given in terms of a bi-local integral of a power law factor, with an exponent parameter s, multiplied by the squared arc length between points on the target manifold. Depending on the choice of s and of dimension, the…

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Open to public
HET Seminar | Natalia Pinzani-Fokeeva, KU Leuven | "Holographic Schwinger-Keldysh effective field theories"
Tue, May 28, 2019, 2:00 pm2:00 pm

Hydrodynamics has been recently reformulated as an effective field theory based on an underlying Schwinger-Keldysh partition function. After an introduction to the formalism, I will show how effective actions of this type can be derived from holography using a mixed signature bulk spacetime whereby an eternal asymptotically anti-de Sitter black…

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HET Seminar | Joseph Maciejko, University of Alberta | "Disordered and deconfined: exotic quantum criticality with Dirac fermions"
Mon, May 6, 2019, 2:30 pm2:30 pm

Critical points of classical second-order phase transitions are thermodynamic phenomena of particular interest, driven by thermal fluctuations and characterized by emergent scale invariance and universal power-law correlations. At zero temperature quantum fluctuations can similarly drive sharp phase transitions between qualitatively distinct…

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HET Seminar | Nathan Benjamin, Princeton University | "A New Twist on the Modular Bootstrap"
Mon, Apr 22, 2019, 2:30 pm2:30 pm

I will discuss new universal bounds on the spectra of two-dimensional unitary, compact conformal field theories coming from the modular bootstrap. In the presence of a twist gap amongst the Virasoro primary operators (where twist is defined as the difference between total conformal dimension and spin), I will show that there is a universal…

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