Here we will keep a list of papers for discussion at the journal club. If you see a paper that seems interesting during the week (up to Wed), just add it to the list and the organizer (Shira) will bring it up during the journal club on Friday. To add a paper, just click on the "edit" button at the bottom of the page.

# This Week

## Feb 26 (Wednesday) - Austin Joyce

### (Cosmological) Bootstrap Bootcamp

How is the physics of Universe's earliest moments encoded in correlations between structures observed at cosmic distances today? How can we re-construct these correlations from general principles like locality, causality, and unitarity? What is the structure of cosmological correlation functions and what consistency conditions must they obey? Come find out.

Papers for discussion for the week after that:

# JCs of the Recent Past

## Feb 21 - Jay Armas

### A certain improvement of the Blandford-Znajek mechanism

I will review the basics of Force Free Electrodynamics and its role in certain astrophysical contexts. I will then discuss the “standard model” of astrophysical jets (the Blandford-Znajek mechanism) for which the energy is extracted from a rotating black hole via plasma currents flowing on magnetic field lines threading the horizon. I will stress that the original formulation of this mechanism is both inconsistent and incomplete and then provide a new consistent formulation based on matched asymptotic expansions. Based on https://arxiv.org/abs/2002.01972.

and we discussed:

- A dynamical mechanism for the Page curve from quantum chaos (Liu, Vardhan)
- Transcending the ensemble: baby universes, spacetime wormholes, and the order and disorder of black hole information (Marolf, Maxfield)
- Hydrodynamics for charge density waves and their holographic duals (Armas, Jain)

## Feb 14 - Antonio Rotundo

### Islands and averaging in the 3-qutrit code

I review recent progress towards a solution of the information paradox, highlighting some aspects that I find confusing. Then I briefly recall how, in the past, quantum error correcting codes have proven useful to make sense of certain confusing properties of holography. Finally, I conclude with some preliminary ideas Ben, Dora and I have been recently discussing on how to reproduce some of the confusions we face in evaporating black holes in a simple quantum error correcting code.TBA

and we discussed:

- Eigenstate Thermalization and Disorder Averaging in Gravity (Pollack, Rozali, Sully, Wakeham)
- Chaos and complementarity in de Sitter space (Aalsma, Shiu)

## Feb 7 - Beatrix Muhlmann

### Gravitational Anomalies in nAdS_2/nCFT_1

I will discuss some recent work with Alejandra in the framework of nAdS_2/nCFT_1. We revisit the holographic description of the near horizon geometry of the BTZ black hole in AdS_3 gravity with a gravitational Chern Simons term included. A dimensional reduction of this three dimensional theory allows us to examine how the UV data of the black hole are captured by the IR data and in particular where inside the 2D CFT the nCFT_1 sits.

and we discussed

- Holographic Order from Modular Chaos (de Boer, Lamprou)
- Matter Couplings and Equivalence Principles for Soft Scalars (Bonifacio, Hinterbichler, Johnson, Joyce, Rosen)
- Modular Hamiltonians for Euclidean Path Integral States (Balakrishnan, Parrikar)
- Distributions in CFT I. Cross-Ratio Space (Kravchuk, Qiao, Rychkov)

## Jan 31 - Claire Zukowski

### Wilson Lines in 3D de Sitter

I will discuss some recent work on constructing local probes in de Sitter, using the Chern-Simons formulation of 3D gravity. We construct Wilson lines in the static patch of Euclidean dS_3 gravity, built with non-unitary representations of so(4) and evaluated using certain states that satisfy a singlet condition. This allows us to reproduce the Green’s functions of massive scalar fields in de Sitter, the construction of bulk fields, and the quasinormal mode spectrum. I will also discuss the interpretation of our results in Lorentzian signature via an analytic continuation to SL(2,C) Chern-Simons theory.

and we discussed

- Double-Scaling Limit in Principal Chiral Model: a New Non-Critical String? (Kazakov, Sobko, Zarembo)
- Gravitational Wilson Lines in 3D de Sitter (Castro, Sabella-Garnier, Zukowski)

## Jan 17 - Vassilis Anagiannis

### Studying convolutional neural networks (CNNs) by using tensor networks.

I will discuss work in progress about using tools and ideas from the language of tensor networks and quantum mechanics to study a certain class of convolutional neural networks (CNNs) which are widely used in machine learning classification tasks.

and we discussed

- On the exact entropy of N=2 black holes (Gomes, het Lam, Mathys)
- Gravitational Collider Physics (Baumann, Chia, Porto, Stout)
- A Conjecture on the Minimal Size of Bound States (Freivogel, Gasenzer, Hebecker, Leonhardt)
- Real-time Dynamics of Plasma Balls (Bantilan, Figueras, Mateos)

# JCs of the past

This has been restored from the backup of our previous referata website.

Journal Clubs of Spring 2015

Journal Clubs of Fall 2015

Journal Clubs of Spring 2016

Journal Clubs of Fall 2016

Journal Clubs of Spring 2017

Journal Clubs of Fall 2017

Journal Clubs of Spring 2018

Journal Clubs of Fall 2018

Journal Clubs of Spring 2019

Journal Clubs of Fall 2019