What is new in gravity?

Contribution List

1. Conformal Carroll scalar actions

Gerben Oling

10/08/2022, 13:30

I will discuss recent approaches to Carroll geometry and its applications to field theory and gravity. Carroll symmetries appear from an ultra-local limit of Lorentz symmetries, and we can use this to systematically construct theories coupled to Carroll background geometry. Specifically, I will discuss recent work on constructing concrete scalar field theories with conformal Carroll...

2. A stable and causal model of magnetohydrodynamics

Jay Armas

10/08/2022, 14:45

Magnetohydrodynamics (MHD) is a theory with a broad range of applications, from plasma physics to heavy-ion collisions and astrophysics. In this talk, I will show how methodologies in formal hydrodynamics allows to reformulate MHD in terms of symmetry considerations. In particular, I will show that MHD can be viewed as a theory of superfluidity and highlight its usefulness as a simpler way of...

3. Islands and gravity in two dimensions

Watse Sybesma

10/08/2022, 16:30

The island formula, also known as Quantum Extremal Surface prescription, provides a new perspective on old paradoxes in semi-classical gravity. Gravity in two dimensions is successful in delivering analytically tractable models of semi-classical gravity and therefore provides an arena to test and apply the island formula. I discuss some recent developments in this context that I believe are exciting.

4. Non-relativistic corners of N=4 super Yang-Mills

Stefano Baiguera

10/08/2022, 16:55

I consider limits of N=4 super Yang-Mills that approach BPS bounds. These limits result in non-relativistic theories that describe the effective dynamics near the BPS bounds and upon quantization are known as Spin Matrix theories. In this talk, I will present convenient methods to determine the interacting Hamiltonian of these theories, proving the positivity of their spectrum. This approach...

5. Fractons on curved spacetime

Emil Have

10/08/2022, 17:30

Fracton phases of matter are characterised by excitations with restricted mobility. While much of their theoretical description remains shrouded in mystery, a robust line of attack involves their spacetime symmetries and their coupling to geometric backgrounds which realise these symmetries locally. One class of fracton theories derive their mobility constraints from a conserved dipole moment....

6. Quantum Critical Membranes and Gravity

Ziqi Yan

10/08/2022, 17:55

I will review the challenges of quantizing supermembranes and the proposal of quantum critical membrane as a candidate high-energy completion. Quantum critical membranes are described by a renormalizable worldvolume theory exhibiting anisotropy in the worldvolume space and time. I will discuss the quantization of a three-dimensional Lifshitz sigma model associated with the matter sector of...

7. The Case for Non-Lorentzian Strings

Jelle Hartong

11/08/2022, 09:00

Non-Lorentzian strings are strings that move in a target space-time that has a non- Lorentzian metric structure defined on it. Some of these strings are described by worldsheet CFTs and some are described by non-Lorentzian 2D sigma models. Most of these types of strings have so far been obtained as limits of ordinary string theory but their notion and definition can be given independently of...

8. What is new in black hole jets?

Maria Rodriguez

11/08/2022, 10:15

One of the leading mechanisms powering relativistic black hole jets is the Blandford–Znajek (BZ) process. Inspired by its success we constructed energy extracting models for black holes in five space-time dimensions. In this talk an overview will be given of recently discovered set of solutions to the force-free electrodynamic equations representing plasma-magnetospheres for slowly rotating...

9. New phases of N=4 SYM at finite chemical potential

Oscar Dias

11/08/2022, 11:30

We do a systematic search of supergravity solutions that, via the AdS5/CFT4 correspondence, are dual to thermal states in N=4 SYM at finite chemical potential. These solutions dominate the microcanonical ensemble and are required to ultimately reproduce the microscopic entropy of AdS black holes. Using a mix of analytical and numerical methods, we construct and study static charged hairy...

10. Gravity as a double copy of gauge theory

Ricardo Monteiro

11/08/2022, 14:00

Relations expressing gravity as a "double copy" of gauge theory appeared first in string theory, and have been used to compute scattering amplitudes in theories of gravity, with applications to both theory and phenomenology. I will discuss how the double copy extends to a class of solutions to the equations of motion, including our best known black hole spacetimes, and how this story connects...

11. Metric reconstruction from celestial multipoles

Roberto Oliveri

11/08/2022, 15:15

Multipole moments are important quantities to characterize spacetimes. In General Relativity, the most general vacuum solution with no incoming radiation is parametrized by two sets of infinite multipole moments. In this talk I will show that non- radiative regions of spacetimes are completely characterized by a set of conserved celestial charges that consist of the Geroch-Hansen multipole...

12. Tidal deformation of a binary system induced by a Kerr black hole

Gianluca Grignani

11/08/2022, 17:00

Thanks to the next generation of gravitational wave detectors, LISA and ET, that will explore the mHz to 10Hz band, it will be possible to observe signals from extreme mass ratio inspirals (EMRIs) of massive black holes and stars/stellar-mass black holes mergers. If the EMRI system is not isolated and it is influenced by another astrophysical object such as a supermassive black hole, the...

13. Precision holography for 5D Super Yang-Mills

Valentina Puletti

12/08/2022, 10:00

With the advent of AdS/CFT and localisation, supersymmetric extensions of Wilson loop (WL) operators came to the forefront as tools to advance our understanding of holography itself. In this talk, I will focus on a circular Wilson loop in maximally supersymmetric Yang-Mills theory (MSYM) living on a 5-sphere. This operator preserves 1/2 of the supercharges of the theory and its vacuum...

14. Celestial holography on Kerr-Schild backgrounds

Andrea Puhm

12/08/2022, 11:15

The four-dimensional flat space S-matrix takes the form of a two-dimensional correlation function on the celestial sphere when changing from an asymptotic energy- momentum to a boost basis. This motivates the conjecture that quantum gravity in asymptotically flat spacetimes is dual to a co-dimension two celestial CFT. In this talk we test this celestial holography proposal for non-trivial...

15. Exact predictions for orbifolds of AdS/CFT

Konstantin Zarembo

12/08/2022, 14:00

The orbifolds of AdS/CFT have an extra parameter, the theta angle of the vanishing cycle. Localization techniques give concrete predictions for the dual quiver gauge theory, potentially
testable in string theory.

16. Holographic black hole evolution

Larus Thorlacius

12/08/2022, 15:15

We revisit the black hole information problem in the context of the AdS/CFT correspondence. The formation and evaporation of small AdS black holes is governed by unitary time evolution in the dual gauge theory but how does this translate to the gravitational theory? We argue that the eigenstate thermalisation hypothesis can explain the validity of semiclassical gravity for local bulk...