# 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:** Giulia Fardelli (giulia.fardelli@physics.uu.se)

## Talks - Fall 2021

**On the Entanglement Entropy in CFTs and Holography**

**Speaker: **Jacopo Sisti

**Papers:**

- Monodromy Defects in Free Field Theories 2104.01220
- Holographic Entanglement Entropy of the Coulomb Branch 2012.05188
- Corner contributions to holographic entanglement entropy in AdS4/BCFT3 1708.05080

**Date:** 29 October 2021, 1.30 - 3.00 pm

**Location:** Å80127 or Zoom https://uu-se.zoom.us/j/69181515232

**Massive matter and the double copy**

**Speaker: **Ingrid Vazquez-Holm

**Papers:**

- Extracting Einstein from the Loop-Level Double-Copy 2108.06798
- Loop-Level Double-Copy for Massive Quantum Particles 2010.13435

**Date:** 15 October 2021, 1.30 - 3.00 pm

**Location:** Å80101 or Zoom https://uu-se.zoom.us/j/69181515232

**Amplitudes in the eikonal limit, black-hole scattering and radiation**

**Speaker: **Carlo Heissenberg

**Papers:**

- Infrared Divergences and the Eikonal Exponentiation 2105.04594
- The Eikonal Approach to Gravitational Scattering and Radiation at O(G3) 2104.03256
- Radiation Reaction from Soft Theorems 2101.05772
- Universality of ultra-relativistic gravitational scattering 2008.12743

**Date:** 08 October 2021, 1.30 - 3.00 pm

**Location:** Å10132 or Zoom https://uu-se.zoom.us/j/69181515232

**Building gauge theories and Calabi Yaus in diverse dimensions**

**Speaker: **Azeem Hasan

**Abstract:** Minimally supersymmetric gauge theories in various dimensions can be engineered on worldvolume of D-branes probing transverse Calabi Yau singularities. This setup is most well studied for N=1 theories in 4d on D3 branes probing Calabi Yau threefolds. Less well studied are (0,2) theories in 2d on D1 branes probing fourfolds and N=1 matrix models on D(-1) branes probing fivefolds. In this talk I will describe an algorithm (arXiv:2004.13765) that leverages the uniform description of these theories developed in arXiv:1904.07954 to construct (0,2) 2d theories and N=1 0d matrix models and the corresponding geometries starting from better understood 4d N=1 theories and the corresponding 3 folds.

**Papers:**

- Calabi-Yau Products: Graded Quivers for General Toric Calabi-Yaus 2004.13765
- Graded Quivers, Generalized Dimer Models and Toric Geometry 1904.07954

**Date:** 01 October 2021, 1.30 - 3.00 pm

**Location:** ITC 6140 or Zoom https://uu-se.zoom.us/j/69181515232

**Towards F-theory Realizations of Exact MSSM Matter Spectra**

**Speaker: **Muyang Liu

**Abstract:** The exact matter spectrum is a significant characteristic of 4D N=1 F-theory compactification, which is expected to match the particle physics we observe. This spectrum is specified by line bundles cohomologies associated to relevant matter curves under the presence of gauge background. In the study of realistic F-theory geometry, those line bundles in the consideration turn into the so-called root bundles. I will elaborate on the developments of interpretation and computation of root bundles based on work 2102.10115 and 2104.08297.

**Papers:**

- Statistics of Limit Root Bundles Relevant for Exact Matter Spectra of F-Theory MSSMs 2104.08297
- Root Bundles and Towards Exact Matter Spectra of F-theory MSSMs 2102.10115

**Date:** 24 September 2021, 1.30 - 3.00 pm

**Location:** Å80121 or Zoom https://uu-se.zoom.us/u/cdKP2PSxK5

## Talks - Spring 2021

**Recent developments in Jackiw-Teitelboim gravity**

**Speaker: **Rodolfo Panerai

**Abstract:** This talk will be based on [1903.11115] and follow-ups. I will review the connection between JT gravity and random matrix ensembles. At infinite cutoff, the results for arbitrary topologies are captured by the Mirzakhani-Eynard-Orantin topological recursion. At finite cutoff, the theory is described by some integrable deformation of the boundary action, but various questions about the role of nonperturbative corrections are still open. In the last part of the talk, I will briefly describe the results of my upcoming paper on the subject.

**Papers:**

- JT gravity as a matrix integral 1903.11115

**Date:** 04 June 2021, 1.30 - 3.00 pm

**Location:** Zoom

**The Weyl double copy from twistor space**

**Speaker: **Lucile Cangemi

**Abstract:** The aim of the talk is to introduce a specific classical double copy formalism and, following the recent paper [2103.16441], discuss its relation to twistor space. A classical double copy is a procedure that relates certain exact classical solutions in Einstein gravity and electromagnetism. I will briefly recap the development of the formalism of the Weyl double copy and introduce the necessary concepts to derive it from twistor space. The introduction of twistor space will broaden the scope of the original procedure and suggests possible extensions.

**Papers:**

- The Weyl double copy from twistor space 2103.16441

**Date:** 21 May 2021, 1.30 - 3.00 pm

**Location:** Zoom

**The string dual to free N=4 super Yang-Mills**

**Speaker: **Charles Thull

**Abstract:** The aim of this talk is to give an overview of the worldsheet description of the AdS5xS5 string as proposed in [2104.08263]. Starting from the free field description with its spectrally flowed sectors I will present the constraints from gauge fixing and quantization and discuss the resulting physical spectrum. Evidence is given that this spectrum matches with the planar spectrum of free maximally supersymmetric Yang-Mills.

**Papers:**

- The String Dual to Free N=4 Super Yang-Mills 2104.08263

**Date:** 07 May 2021, 1.30 - 3.00 pm

**Location:** Zoom

**4D Chern-Simons Theory and Integrability**

**Speaker: **Simon Ekhammar

**Abstract:** The main goal of the talk will be to discuss 4D Chern-Simons and in particular the integrable structure of the theory. I will start by reviewing fundamental concepts in integrability primarily using the canonical example of the XXX-spin. In particular I intend to discuss R-matrices, RTT relations and shortly comment on the relations between the three different realizations of Yangians. Thereafter following the papers 1709.09993, 1802.01579 I will discuss how the same concepts are realized using Chern-Simons gauge theory in 4 dimensions. Depending on time I will shortly also comment on more recent progress in various directions using this formalism.

**Papers:**

- Gauge Theory and Integrability, I 1709.09993
- Gauge Theory and Integrability, II 1802.01579

**Date:** 23 April 2021, 1.30 - 3.00 pm

**Location:** Zoom

**Exact properties of an integrated correlator in N=4 SU(N) SYM**

**Speaker: **Carlos Gustavo Rodriguez Fernandez

**Papers:**

- Exact properties of an integrated correlator in N=4 SU(N) SYM 2102.09537

**Date:** 09 April 2021, 1.30 - 3.00 pm

**Location:** Zoom

**Exact solutions in N=2 D=4 Gauged Supergravity coupled to abelian vector multiplets**

**Speaker: **Davide Astesiano

**Papers:**

- Super throats with non trivial scalars 2003.11582
- De Sitter magnetic black hole dipole with a supersymmetric horizon 2012.04362

**Date:** 19 March 2021, 1.30 - 3.00 pm

**Location:** Zoom

**Classical de Sitter solutions between two mirrors: A new recipe?**

**Speaker: **Daniel Panizo Pérez

**Abstract:** In this talk, we will take a look at new results from type IIA supergravity compactifications. A four-dimensional space with positive cosmological constant is obtained by solving the ten-dimensional equations of motion. To achieve these results, a characteristic topology and O-planes are required. However, this achievement is not free of controversy, as some of its features are not well-understood or are incompatible with no-go theorems. We will introduce all required ingredients that are present in these results and then examine their properties.

**Papers:**

- Classical de Sitter Solutions of Ten-Dimensional Supergravity 1812.04147
- No classical (anti-)de Sitter solutions with O8-planes 1902.08209
- New de Sitter Solutions in Ten Dimensions and Orientifold Singularities 1911.04498
- What if string theory has no de Sitter vacua? 1804.01120
- Smeared versus localised sources in flux compactifications 1009.1877
- Daniel's notes

**Date:** 05 March 2021, 1.30 - 3.00 pm

**Location:** Zoom

**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 values 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:**

- Chern-Simons Theory and the R-Matrix 1905.03263

**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**

**Speaker: **Vladimir Bashmakov

**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:**

- Stringy Canonical Forms 1912.08707

**Date:** 06 March 2020, 1.30 - 3.00 pm

**Location:** Room Å4003

**Sphere Packing and Quantum Gravity II**

**Speaker: **Alexander Söderberg

**Papers:**

- Sphere Packing and Quantum Gravity 1905.01319

**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:**

- Sphere Packing and Quantum Gravity 1905.01319
- Modular Bootstrap Revisited 1608.06241

**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