Fall 2019
KCL Strings Journal Club Fall 2019

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Fall 2019 Journal Club Here's a summary of all the activity of our Journal Club during the Fall 2019 term.

Summary

December 6:Gerben Venken (KU Leuven)

Title: EFT Constraints from Charged Black Hole Evaporation in de Sitter space

Abstract:

In the Swampland philosophy of constraining effective field theories from black hole mechanics, we study charged black hole evaporation in 4D de Sitter space. We establish how the black hole mass and charge change over time due to both Hawking radiation and Schwinger pair production as a function of the masses and charges of the elementary particles in the theory. Demanding that large charged black holes evaporate back to empty de Sitter space, in accordance with the thermal picture of the de Sitter static patch, leads to a lower bound on the mass of charged particles. This bound is satisfied by the charged spectrum of the Standard Model. We discuss implications for the cosmological hierarchy problem, inflation, and holography in de Sitter space.

This talk is based on https://arxiv.org/abs/1910.01648 with Miguel Montero and Thomas Van Riet.

Papers discussed:

  1. Emergent unitarity in de Sitter from matrix integrals (Cotler, Jensen)
  2. Quenched vs Annealed: Glassiness from SK to SYK (Baldwin, Swingle)
  3. Bosonic Symmetries of (2,0) DLCQ Field Theories (Neil, Lipstein, Rishi, Paul)

November 29: Paul Richmond

Title: Localization of the action in AdS/CFT

Abstract:

I will present the paper https://arxiv.org/abs/1906.11249 by P Benetti Genolini, J M Perez Ipina and J Sparks, where they derive a simple formula for the action of any supersymmetric solution to minimal gauged supergravity in the AdS4/CFT3 correspondence.

Papers discussed:

  1. Thermodynamic Bethe Ansatz for Fishnet CFT (Basso, Ferrando, Kazakov, Zhong)
  2. Areas and entropies in BFSS/gravity duality (Anous, Karczmarek, Mintun, Van Raamsdonk, Way)
  3. Entanglement Entropy in Jackiw-Teitelboim Gravity (Jafferis, Kolchmeyer)
  4. Replica Wormholes and the Entropy of Hawking Radiation (Almheiri, Hartman, Maldacena, Shaghoulian, Tajdini)
  5. Replica wormholes and the black hole interior (Penington, Shenker, Stanford, Yang)

November 22: Bidisha Chakrabarty (ICTS)

Title: Nonlinear Langevin dynamics via holography

Abstract:

I will discuss the leading non-linear corrections to the Brownian motion of a heavy quark moving through a strongly coupled CFT plasma (bath) using holographic Schwinger-Keldysh path integral. The bulk spacetime in this formalism is a double copy of AdS black brane with a doubled string that probes it. The string stretches from two AdS boundaries and loops around a ‘horizon cap’ connecting the horizons of the black branes. Evaluating the Nambu Goto action on this doubled string configuration results in the (quartic) influence phase of the heavy quark. The influence phase passes non-trivial consistency conditions arising from the underlying unitarity and thermality of the bath. The local effective theory obeys recently developed non-linear fluctuation dissipation relation that relates the non-Gaussianity of thermal noise to the thermal jitter in the damping constant of the Brownian particle.

Papers discussed:

  1. Effective Quantum Field Theory for the Thermodynamical Bethe Ansatz (I. Kostov)
  2. Confinement as Analytic Continuation Beyond Infinity (M. Yamazaki, K. Yonekura)

November 15: Nozomu Kobayashi

Title: Holographic dual of OPE blocks

Abstract:

Operator Product Expansion (OPE) is one of the fundamental features in CFT and it can be decomposed into the irreducible representations of the conformal group, so called OPE blocks. Though the form of scalar OPE blocks was derived a long time ago by Ferarra, Gatto and Grillo in 1970's, it was not until recently that some groups pointed out that OPE blocks have natural holographic duals. I will review the derivation of scalar OPE blocks and explain their holographic duals following [1604.07383] by Cunha and Guica.

Papers discussed:

  1. Conformally invariant averaged null energy condition from AdS/CFT (Iizuka, Ishibashi, Maeda)
  2. Information Flow in Black Hole Evaporation (Chen, Fisher, Hernandez, Myers, Ruan)
  3. Eigenvectors from Eigenvalues (Denton, Parke, Tao, Zhang)

November 8: Damian Galante

Title: Effective field theories for hydrodynamics

Abstract:

I will review recent attempts to develop effective field theories that describe systems in their hydrodynamical regime. I will motivate why this is desirable and show how to construct these effective actions based on the symmetries of the problem. If time allows, I will also explore the connections of this formalism with recent ideas related to quantum chaos.

Papers discussed:

  1. λφ4 in dS (Gorbenko, Senatore)
  2. Deriving the AdS3/CFT2 Correspondence (Eberhardt, Gaberdiel, Gopakumar)
  3. On the logarithmic coefficient of the entanglement entropy of a Maxwell field (Casini, Huerta, Magan, Pontello)
  4. A general definition of JTa -- deformed QFTs (Anous, Guica)
  5. Eigenvalue estimates for multi-form modified Dirac operators (George, et al)

November 1: Andrea Cavaglia

Title: Some integrability magic for classical strings

Abstract:

I will present the paper https://arxiv.org/abs/1908.03219 by S. Komatsu,
where it is shown how to use integrability to compute classical 3 point functions for strings and Liouville theory.

Papers discussed:

  1. Dual Separated Variables and Scalar Products (Kolya, et al)
  2. The Cosmological Bootstrap: Weight-Shifting Operators and Scalar Seeds (Baumann, Duaso Pueyo, Joyce, Lee, Pimentel)
  3. Notes on the complex Sachdev-Ye-Kitaev model (Gu, Kitaev, Sachdev, Tarnopolsky)
  4. Probing the EVH limit of supersymmetric AdS black holes (Goldstein, Jejjala, Lei, van Leuven, Li)

October 25: Dionysios Anninos

Title: Comments on Entanglement Entropy and Sphere Partition Functions

Abstract:

I will comment on Entanglement Entropy and its relation to the Sphere Partition Function.

Papers discussed:

  1. Liouville Theory, AdS2 String, and Three-Point Functions (Komatsu)
  2. Throat destabilization (for profit and for fun) (Bena, Buchel, Lust)

October 18: Tarek Anous (UvA)

Title: A geometric interpretation of the irrelevant JT deformation

Abstract:

A certain class of irrelevant deformations of two dimensional quantum field theories have received some interest over the past few years, since they can surprisingly be exactly solved. The lore behind irrelevant deformations implies that they are plagued by short distance ambiguities which proliferate along the RG flow, in seeming contradiction of this fact. In the specific case of the irrelevant $T\bar{T}$ deformation, a simple explanation for this seeming contradiction is that the deformation can be reinterpreted as coupling the QFT to a precise theory of topological gravity. Since we have added no new degrees of freedom, the solubility of the irrelevant deformation becomes manifest. In the journal club, I will review the $T\bar{T}$ story and will extend it to another set of irrelevant deformations which explicitly break Lorentz invariance, namely the $JT$ deformation.

Papers discussed:

  1. Traversable wormholes in AdS and bounds on information transfer (Damian, et al)
  2. JT gravity as a matrix integral (Saad, Shenker and Stanford)

October 11: Alejandro Cabo-Bizet

Title: Black Hole Entropy

Papers discussed:

  1. Supersymmetric phases of 4d N=4 SYM at large N (Alejandro, Sameer)
  2. Roadmap on Wilson loops in 3d Chern-Simons-matter theories (Maxime, Nadav, et al)
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