Events Archive

HET Seminar | Zohar Komargodski, Stony Brook | "Dynamics in 2+1 Dimensions" | PCTS Seminar Room
Fri, Dec 1, 2017, 1:45 pm1:45 pm

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…

HET Seminar at IAS | Andrew Liam Fitzpatrick, Boston University | “Information Loss and Bulk Reconstruction in AdS_3/CFT_2”
Mon, Nov 27, 2017, 2:30 pm2:30 pm

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…

HET Seminar | Lorenzo Di Pietro, Perimeter Institute | "Loops in AdS from Hamiltonian approach" | PCTS Seminar Room
Mon, Nov 20, 2017, 2:30 pm2:30 pm

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…

HET Seminar | Petr Kravchuk, Caltech | “6j symbols and conformal blocks” | PCTS Seminar Room
Tue, Nov 14, 2017, 1:30 pm1:30 pm

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…

HET Seminar at IAS | Roji Pius, Perimeter Institute | "Quantum Closed Superstring Field Theory and the Weil-Petersson Symplectic Geometry"
Mon, Nov 13, 2017, 2:30 pm2:30 pm

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…

HET Seminar | Shira Chapman, Perimeter Institute | "Complexity in holography and QFT" | PCTS Seminar Room
Fri, Nov 10, 2017, 1:45 pm1:45 pm

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…

HET Seminar | Matteo Lotito, UCincinnati | "Uncovering flavor of N SCFTs through geometry" | Jadwin A06
Tue, Nov 7, 2017, 1:30 pm1:30 pm

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,…

HET Seminar | David Lowe, Brown | "Black hole holography and mean field evolution" | PCTS Seminar Room
Mon, Nov 6, 2017, 2:30 pm2:30 pm

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…

HET Seminar at IAS | Kyle Cranmer, NYU | “What does the Revolution in Artificial Intelligence Mean for Physics?”
Mon, Oct 30, 2017, 2:30 pm2:30 pm

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…

HET Seminar | Emil Akhmedov, ITEP Moscow | "Surprises of quantization in de Sitter space" | PCTS Sem Rm
Mon, Oct 30, 2017, 11:00 am11:00 am

I will talk about loop infrared effects in de Sitter QFT. Namely about their types, physical meaning and origin and also about their resumation. 

HET Seminar | Hong Liu, MIT | "A hydrodynamical theory for quantum many-body chaos" | PCTS Seminar Room
Fri, Oct 27, 2017, 1:45 pm1:45 pm

Recently there has been progress on characterizing chaos in quantum many-body systems by studying commutators 

of generic few-body operators in a thermal state. In this talk we introduce an effective theory, in fact a hydrodynamical theory, 

to describe the "butterfly effect" exhibited by these commutators. 

HET Seminar | Fabio Sanches, UC Berkeley | "Bulk locality from subregion duality" | PCTS Seminar Room
Tue, Oct 24, 2017, 4:00 pm4:00 pm

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,…

HET Seminar | Eduardo Teste, Instituto Balseiro Centro Atomico Bariloche | "Entropic A theorem and the Markov property of the vacuum" | PCTS Seminar Room
Mon, Oct 23, 2017, 2:30 pm2:30 pm

A state is said to be Markovian if it fulfil 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 …

HET Seminar at IAS | Anna Karlsson, Member, School of Natural Sciences, IAS | "TBA"
Fri, Oct 20, 2017, 1:45 pm1:45 pm
HET Seminar | Alexander Vilenkin, Tufts U. | "Black holes from cosmic inflation" | PCTS Seminar Rm
Mon, Oct 16, 2017, 2:30 pm2:30 pm

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…

HET Seminar | Nima Lashkari, MIT | "Diffeomorphisms and RG monotones" | PCTS Seminar Rm
Fri, Oct 13, 2017, 1:45 pm1:45 pm

I discuss the amount of information in quantum field theory states reduced to a region, that cannot be recovered from its subregion density matrices. One can reconstruct the density matrix from its subregions using two approaches: scaling maps and recovery maps. The vacuum of a conformal field theory is a quantum Markov state and the fixed…

Special HET Seminar at IAS | Piljin Yi, Korean Institute for Advanced Study | “Indices, Localization, Rational Invariants, and H-Saddles”
Tue, Oct 10, 2017, 1:45 pm1:45 pm

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…

HET Seminar at IAS | Thomas Hartman, Cornell University | “Causality and the Length Operator”
Mon, Oct 9, 2017, 2:30 pm2:30 pm

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…

Special HET Seminar at IAS | Irene Valenzuela, Max-Planck-Institut für Physik | "Contraints on Particle Physics and Inflation from Quantum Gravity Conjectures"
Thu, Oct 5, 2017, 1:45 pm1:45 pm

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…

HET Seminar at IAS | Grant Remmen, Caltech | “Twofold Symmetries and Simplification of the Gravity Action”
Mon, Oct 2, 2017, 2:30 pm2:30 pm

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…