# Journal Club

The target group of the Theoretical Physics Journal Club are PhD students and postdocs doing research on different topics of theoretical physics. Here we can meet to learn and discuss classical or new topics of theoretical physics.
Organizer: Matthew Magill (matthew.magill@physics.uu.se)

## Talks - Spring 2021

3D Chern-Simons theory and the R matrix

Speaker: Maor Ben-Shahar
Abstract: I will explain the details of the construction of a classical r-matrix from 3D Chern-Simons theory following [1905.03263]. The construction relies on imposing unconventional gauge choices and boundary conditions on $R^2 \times I$. These choices imply that expectation valued of knots are always well-defined (no framing anomaly), but are not knot-invariants. Finally, we will extend the paper a little by discussing corrections to all orders in $\hbar$.
Papers:

Date: 19 February 2021, 1.30 - 3.00 pm
Location: Zoom

More on holographic correlators: Twisted and dimensionally reduced structures

Speaker: Andrea Manenti
Papers:

• More on holographic correlators: Twisted and dimensionally reduced structures 2101.04114

Date: 05 February 2021, 1.30 - 3.00 pm
Location: Zoom

Celestial Amplitudes and the Double Copy

Speaker: Lucia Garozzo
Abstract: Celestial amplitudes are obtained by performing a change of basis on traditional scattering amplitudes. They behave as conformal correlators, giving rise to the speculation that there is a CFT living on the celestial sphere at the null boundary of flat spacetime, and thus a possible holographic description of flat space quantum gravity. I will give an overview of the topic and present the result of the paper 2007.15027, where the authors find a simple prescription to relate gauge theory and gravity celestial amplitudes at tree level.
Papers:

• A Double Copy for Celestial Amplitudes 2007.15027

Date: 22 January 2021, 1.30 - 3.00 pm
Location: Zoom

## TALKS - FALL 2020

Exploring standard like models
Speaker: Robin Schneider

Papers:

• Explore and Exploit with Heterotic Line Bundle Models 2003.04817

Date: 03 December 2020, 1.30 - 3.00 pm
Location: Zoom

Large p explorations. From SUGRA to big STRINGS in Mellin space
Speaker: Giulia Fardelli

Papers:

• Large p explorations. From SUGRA to big STRINGS in Mellin space 2007.09176

Date: 20 November 2020, 1.30 - 3.00 pm
Location: 80101, Zoom

What can Spinning Particles say about Kerr Black Holes?
Speaker: Paolo Pichini

Papers:

• From Scattering Amplitudes to Classical Physics: Universality, Double Copy and Soft Theorems 1903.12419
• Tree-Level Unitarity Constraints on the Gravitational Couplings of Higher-Spin Massive Fields 9408073

Date: 13 November 2020, 1.30 - 3.00 pm
Location: 80101, Zoom

Double copy in string and field theories
Speaker: Yong Zhang

Date: 6 November 2020, 1.30 - 3.00 pm
Location: 80101, Zoom

Superconformal kinematics in four dimensions
Speaker: Andrea Manenti

Papers:

• Differential operators for superconformal correlation functions 1910.12869
• R-current three-point functions in 4d N=1 superconformal theories 1804.09717
• Implications of ANEC for SCFTs in four dimensions 1905.09293

Date: 23 October 2020, 1.30 - 3.00 pm
Location: Häggsalen, Zoom

Computing (multiloop) Feynman integrals through analytic and numerical methods
Speaker: Martijn Hidding
Papers:

• All orders structure and efficient computation of linearly reducible elliptic Feynman integrals 1712.04441
• Evaluating two-loop non-planar master integrals for Higgs + jet production with full heavy-quark mass dependence 1907.13156
• The complete set of two-loop master integrals for Higgs + jet production in QCD 1911.06308
• DiffExp, a Mathematica package for computing Feynman integrals in terms of one-dimensional series expansions 2006.05510

Date: 16 October 2020, 1.30 - 3.00 pm
Location: Polhemsalen, Zoom

On-shell constructions of nonlinear sigma model
Speaker: Zhewei Yin

Date: 09 October 2020, 1.30 - 3.00 pm
Location: Häggsalen, Zoom

Vertex operators for the 11D pure spinor superparticle
Speaker: Max Guillen

Date: 02 October 2020, 1.30 - 3.00 pm
Location: Polhemsalen, Zoom

Introducing 3d N=1 QFTs

Date: 25 September 2020, 1.30 - 3.00 pm
Location: ITC room 2247, Zoom

## Talks - Spring 2020

Fermionic Localization of the Schwarzian Theory
Speaker: Lorenzo Ruggeri
Papers:

• Fermionic Localization of the Schwarzian Theory 1703.04612
• Conformal symmetry and its breaking in two dimensional Nearly Anti-de-Sitter space 1606.01857

Date: 11 March 2020, 1.30 - 3.00 pm
Location: Room Å80101

Stringy Canonical Forms
Speaker: Fei Teng
Papers:

Date: 06 March 2020, 1.30 - 3.00 pm
Location: Room Å4003

Sphere Packing and Quantum Gravity II
Speaker: Alexander Söderberg
Papers:

Date: 28 February 2020, 1.30 - 3.00 pm
Location: Room Å4003

Walls, Anomalies, and (De)Confinement in Quantum Anti-Ferromagnets
Speaker: Arash Arabi Ardehali
Papers:

• Walls, Anomalies, and (De)Confinement in Quantum Anti-Ferromagnets 1706.05731

Date: 21 February 2020, 1.30 - 3.00 pm
Location: Room Å4003

Sphere Packing and Quantum Gravity
Speaker: Alexander Söderberg
Papers:

Date: 14 February 2020, 1.30 - 3.00 pm
Location: Room Å4003

Froissart bound for/from CFT Mellin amplitudes
Speaker: Parijat Dey
Papers:

• Froissart bound for/from CFT Mellin amplitudes: 1911.05974

Date: 07 February 2020, 1.30 - 3.00 pm
Location: Room Å4003

GSO projections via SPT phases
Speaker: Luca Cassia
Papers:

• GSO projections via SPT phases: 1908.04805
• Topological Superconductors on Superstring Worldsheets: 1911.11780

Date: 24 January 2020, 1.30 - 3.00 pm
Location: Room Å4003

Higher U(1) Charge Models in type IIB and their F-theory lift
Speaker: Damián K. Mayorga Pena
Abstract:
We construct models with U(1) gauge group and matter with charges up to 6, in the context of type IIB compactifications. We show explicitly that models with charges up to 4 can be derived from corresponding models in F-theory by applying the Sen weak coupling limit. We derive which type IIB models should be the limit of charge 5 and 6 F-theory models. Explicit six dimensional type IIB models with maximal charge 5 and 6 are constructed on an algebraic K3 surface that is the double cover of CP^2. By using type IIB results we are also able to rediscover the F-theory charge 4 model in a straightforward way.
Date: 15 January 2020, 1.30 - 3.00 pm
Location: Room Å80101

## Talks - Fall 2019

New Progress in Entanglement Wedge Reconstruction
Papers:

• Islands outside the horizon [https://arxiv.org/abs/1910.11077]
• Entanglement Wedge Reconstruction and the Information Paradox [https://arxiv.org/abs/1905.08255]

Date: 13 December  2019, 1.30-3.00 pm
Location: Room Å4003

What is spin?
Speaker: Simon Streib
Papers:

•  "Angular momentum in spin-phonon processes" by D. A. Garanin and E. M. Chudnovsky [https://journals.aps.org/prb/abstract/10.1103/PhysRevB.92.024421]
• "The photon angular momentum controversy: Resolution of a conflict
between laser optics and particle physics" by E. Leader [https://www.sciencedirect.com/science/article/pii/S0370269316001945]
• "What is spin?" by H. C. Ohanian [https://aapt.scitation.org/doi/10.1119/1.14580]
• "How Electrons Spin" by C. Sebens [https://arxiv.org/abs/1806.01121]

Date: 29 November  2019, 1.30-3.00 pm
Location: Room Å4003
Abstract: Spin is an important property of elementary particles and also of quasiparticles, such as magnons and phonons. A physical picture of spin is not available for point particles, but it is for fields. I will discuss as examples the angular momentum of phonons, photons, and electrons based on their corresponding fields: the elastic, electromagnetic, and Dirac fields. In the case of the photon, the question if it is even possible to separate the angular momentum into orbital and spin contributions in a gauge-invariant way has only recently been resolved. The goal of this talk is to present a unified picture of what spin actually is and to invite discussion and criticism of this point of view.

Holographic Complexity: Stretching the Horizon of an Evaporating Black Hole
Speaker: Watse Sybesma
Date: 22 November  2019, 1.30-3.00 pm
Location: Room Å4003
Abstract: Holographic complexity can be obtained from probing beyond the horizon of a black hole using a specific prescription. Holographic complexity is conjectured to be dual to a notion of complexity as defined in quantum circuits, but it can also be interesting purely in the context of black holes, as I will argue, due to its relation to black hole entropy. In this talk I present the holographic complexity of an evaporating black hole in the semi-classical Russo-Thorlacius-Susskind (RST) model. By considering the stretched horizon of the evolving black hole, one obtains sensible results for the rate of growth of the complexity, with an early onset of order the black hole scrambling time followed by an extended period where the rate of growth tracks the shrinking area of the stretched horizon as the black hole evaporates.

Geometric engineering of 6D SUGRA and SCFT's using F-theory
Speaker: Paul-Konstantin Oehlmann
Date: 15 November 2019, 1.30-3.00 pm
Location: Room Å4004

Supersymmetric Wilson loops in two dimensions and duality
Speaker: Rodolfo Panerai
Papers: https://arxiv.org/abs/1812.01315 by Rodolfo Panerai, Matteo Poggi, Domenico Seminara
Date:  8 November 2019, 1.30-3.00 pm
Location: Room 1113 ITC

Scattering in the High Energy Limit of Planar N=4 SYM
Speaker: Bram Verbeek
Papers:

• https://arxiv.org/abs/1606.08807 by Vittorio Del Duca, Stefan Druc, James Drummond, Claude Duhr, Falko Dulat, Robin Marzucca, Georgios Papathanasiou, Bram Verbeek
• https://arxiv.org/abs/1801.10605 by Vittorio Del Duca, Stefan Druc, James Drummond, Claude Duhr, Falko Dulat, Robin Marzucca, Georgios Papathanasiou, Bram Verbeek
• https://arxiv.org/abs/1811.10570 by Robin Marzucca, Bram Verbeek

Date: 25 October 2019, 1.30-3.00 pm
Location: Room Å4003

Punctured horizons
Speaker: Pieter Bomans
Paper:  TBA
Date: 18 October  2019, 1.30-3.00 pm
Location: Room 1113 ITC
Abstract: In this talk we study the IR dynamics of M- and D-branes wrapping a Riemann surface with punctures. From a field theory perspective this is a very natural operation which results in many interesting IR SCFTs. We present the holographically dual picture of these SCFTs and discuss how to treat the singularities from a lower dimensional supergravity point of view. In all cases the IR dynamics are governed by a single second order equation -- the Liouville equation. As an example we study in detail a class of $\mathcal{N}=1$ SCFTs obtained by wrapping M5-branes on complex curves with prescribed singularities. We present explicit $AdS_5$ backgrounds describing the IR fixed points of these theories at large $N$ and for a subset of these solutions we explicitly construct the dual four dimensional quiver gauge theories.

Instantons in various dimensions
Speaker: Nicolo Piazzalunga
Date: 11 October 2019, 1.30-3.00 pm
Location: Room 2245 ITC

Entanglement Entropy in String Theory
Speaker: Usman Naseer
Date: 4 October 2019, 1.30-3.00 pm
Location: Room 1145 ITC

Ultraviolet Structure of N=8 Supergravity
Speaker: Alex Edison
Papers:

• https://arxiv.org/abs/1804.09311 by Zvi Bern, John Joseph Carrasco, Wei-Ming Chen, Alex Edison, Henrik Johansson, Julio Parra-Martinez, Radu Roiban, Mao Zeng
• https://arxiv.org/abs/1909.02003 by Alex Edison, Enrico Herrmann, Julio Parra-Martinez, Jaroslav Trnka

Date: 27 September 2019, 1.30-3.00 pm
Location: Room Å80101

## Talks - Spring 2019

Thermal CFTs in momentum space
Speaker: Andrea Manenti
Papers: https://arxiv.org/abs/1905.01355 by Andrea Manenti
Date: 24 May 2019, 1.30-3.00 pm
Location: Room Å2003

Comments on One-Form Global Symmetries and Their Gauging in 3d and 4d
Speaker: Konstantina Polydorou
Papers: https://arxiv.org/abs/1812.04716 by Po-Shen Hsin, Ho Tat Lam, Nathan Seiberg
Date: 17 May 2019, 1.30-3.00 pm
Location: Room Å2003

The light-ray OPE and conformal colliders
Speaker: Tobias Hansen
Papers:

• https://arxiv.org/abs/1904.05905 by Murat Kologlu, Petr Kravchuk, David Simmons-Duffin, Alexander Zhiboedov
• https://arxiv.org/abs/1905.01311 by Murat Kologlu, Petr Kravchuk, David Simmons-Duffin, Alexander Zhiboedov

Date: 10 May 2019, 1.30-3.00 pm
Location: Room Å2003

Massive On-Shell Supersymmetric Scattering Amplitudes
Speaker: Gustav Mogull
Papers:

• https://arxiv.org/abs/1902.07204 by Aidan Herderschee, Seth Koren, Timothy Trott
• https://arxiv.org/abs/1902.07205 by Aidan Herderschee, Seth Koren, Timothy Trott

Date: 3 May 2019, 1.30-3.00 pm
Location: Room Å2003

Schur correlation functions on S3 x S1
Speaker: Anastasios Gorantis
Papers: https://arxiv.org/abs/1903.03623 by Yiwen Pan, Wolfger Peelaers
Date: 26 April 2019, 1.30-3.00 pm
Location: Room Å2003

A New SU(2) Anomaly
Speaker: Luca Cassia
Papers: https://arxiv.org/abs/1810.00844 by Juven Wang, Xiao-Gang Wen, Edward Witten
Date: 12 April 2019, 1.30-3.00 pm
Location: Room Å2003

On W-representations of β- and q,t-deformed matrix models
Speaker: Rebecca Lodin
Papers: https://arxiv.org/abs/1901.02811 by A. Morozov
Date: 5 April 2019, 1.30-3.00 pm
Location: Room Å2003

A New SU(2) Anomaly [postponed]
Speaker: Luca Cassia
Papers: https://arxiv.org/abs/1810.00844 by Juven Wang, Xiao-Gang Wen, Edward Witten
Date: 29 March 2019, 1.30-3.00 pm
Location: Room Å2003

Baryons as Quantum Hall Droplets
Papers: https://arxiv.org/abs/1812.09253 by Zohar Komargodski
Date: 15 March 2019, 1.30-3.00 pm
Location: Room Å2003

Twisted Holography
Speaker: Lorenzo Ruggeri
Papers: https://arxiv.org/abs/1812.09257 by Kevin Costello, Davide Gaiotto
Date: 1 March 2019, 1.30-3.00 pm
Location: Room Å4005

Remarks on the Green-Schwarz terms of six-dimensional supergravity theories
Speaker: Matthew Magill
Papers: https://arxiv.org/abs/1808.01334 by Samuel Monnier, Gregory W. Moore
Date: 22 February 2019, 1.30-3.00 pm
Location: Room 1145 ITC

Asymptotic Fragility, Near AdS2 Holography and $T\bar{T}$
Papers: https://arxiv.org/abs/1706.06604 by Sergei Dubovsky, Victor Gorbenko, Mehrdad Mirbabayi
Date: 15 February 2019, 1.30-3.00 pm
Location: Room 1145 ITC

Simplifying large spin bootstrap in Mellin space
Speaker: Parijat Dey
Papers: https://arxiv.org/abs/1709.06110 by Parijat Dey, Kausik Ghosh, Aninda Sinha
Date: 8 February 2019, 1.30-3.00 pm
Location: Room 2215 ITC

Scattering of Spinning Black Holes from Exponentiated Soft Factors
Speaker: Alexander Ochirov
Papers: https://arxiv.org/abs/1812.06895 by Alfredo Guevara, Alexander Ochirov, Justin Vines
Date: 1 February 2019, 1.30-3.00 pm
Location: Room Å4003

Making wormholes traversable using non-local couplings
Speaker: Suvendu Giri
Papers:

• https://arxiv.org/abs/1608.05687 by Gao, Jafferis and Wall
• https://arxiv.org/abs/1704.05333 by Maldacena, Stanford and Yang

Date: 18 January 2019, 1.30-3.00 pm
Location: Room Å4003