Numerical approaches to holography, quantum gravity and cosmology

21 May 2018, 08:00 → 24 May 2018, 18:00 UTC

Higgs Centre for Theoretical Physics

Holographic AdS/CFT duality and lattice gauge theory are leading non-perturbative approaches to investigate quantum gravity and strongly coupled quantum field theories. Extensive work is ongoing to apply both techniques to broader classes of systems, leading to a growing number of connections between them. Numerical analyses in particular are becoming increasingly important as computational capabilities continue to improve, motivating the development and dissemination of new or improved methods. Representative applications range from numerical relativity calculations of black hole dynamics and non-stationary spacetimes dual to far-from-equilibrium QFTs, to lattice studies of gauge theories with near-conformal dynamics, supersymmetry, or a large number of colours. Important successes of these ideas have been found in matching quantum field theory calculations in 0+1 dimensions with string theory predictions in 9+1 dimensions for black hole entropies with large D0-brane charge. Many advances have also been made recently in studying lattice gauge theories with some supersymmetry and near a conformal limit. The purpose of this workshop is to bring together the different communities of theoretical physicists who use numerical methods to investigate these types of questions. The programme of 16 invited talks over four days, 21--24 May, will leave abundant time for discussions and informal exchanges. By reviewing new developments within each community and fostering communication between them we aim to identify common ground, inspire new ideas and stimulate more rapid progress.

Monday 21 May

09:00 → 09:30 Welcome & coffee

09:30 → 12:30 Session 1

09:30 Kaluza-Klein black holes and their role in holography

Speaker: Dr Toby Wiseman (Imperial College, London)

Slides EdinburghTalk.pdf

10:45 Coffee break

11:15 Superstrings on lattice

Speaker: Dr Valentina Forini (City, University of London)

Slides Forini_Edinburgh_18.pdf

12:30 → 14:00 Lunch & discussions

14:00 → 17:20 Session 2

14:00 Numerical methods for solving the Einstein equation in higher dimensions and in AdS with Cauchy evolution

Speaker: Dr Pau Figueras (Queen Mary, University of London)

Slides FiguerasEdinburgh2018.pdf

15:15 Coffee break

15:45 Holographic aspects of loop quantum gravity

Speaker: Dr Norbert Bodendorfer (University of Regensburg)

Slides Bodendorfer_Edinburgh_2018.pdf

Tuesday 22 May

09:30 → 12:30 Session 3

09:30 The non-perturbative phase diagram of the BMN matrix model

We study the maximally supersymmetric plane wave matrix model (the BMN model) at finite temperature, T, and locate the leading phase boundary as the temperature is lowered.

Speaker: Dr Denjoe O'Connor (Dublin IAS)

Slides Denjoe_Edinburg_May_2018_lecture.pdf

10:45 Coffee break

11:15 Supersymmetry gradient flow

Speaker: Dr Daisuke Kadoh (Keio University)

Slides supersymmetry_gradient_flow-2.ppt

12:30 → 14:00 Lunch & discussions

14:00 → 17:00 Session 4

14:00 Lattice quantum gravity and asymptotic safety

Speaker: Dr Jack Laiho (Syracuse University)

Slides Lahio_Edinburgh_2018.pdf

15:15 Coffee break

15:45 Spectral Methods in Causal Dynamical Triangulations

I will discuss the application of spectral analysis, i.e. analysis of the spectrum and eigenvectors of the Laplace-Beltrami operator, in the setting of the Monte-Carlo approach to Quantum Gravity called Causal Dynamical Triangulations (CDT). In particular, applying the method to the analysis of spatial slices shows that the different phases can be characterized by a new order parameter related to the presence or absence of a gap in the spectrum of the Laplace-Beltrami operator, and allows to derive an effective dimensionality of the slices at different scales.

Speaker: Dr Giuseppe Clemente (Pisa University)

Paper https://arxiv.org/abs/1804.02294

Slides DiClementeMain.pdf

Wednesday 23 May

09:30 → 12:30 Session 5

09:30 Anomalous dimensions in conformal systems: non-perturbative gradient flow approach

Speaker: Dr Anna Hasenfratz (University of Colorado)

Slides Anna_Edinburgh_2018.pdf

10:45 Coffee break

11:15 Hierarchies, dynamical supersymmetry breaking & holographic duality

Speaker: Dr Joel Giedt (Rensselaer)

Paper gabella_gherghetta_giedt_0704.3571.pdf giedt_gherghetta_0605212.pdf

Slides hierarchies.pdf

12:30 → 14:00 Lunch & discussions

14:00 → 17:00 Session 6

14:00 Extreme Holography

A massive experimental effort will be devoted in the coming years to the physics of QCD at high energy density and/or high baryon density. Understanding this physics, especially out of equilibrium, is an important theoretical challenge. I will discuss how holography can help us address this challenge. Topics covered will include the far-from-equilibrium dynamics near the QCD critical point and colour superconducting phases. No prior knowledge of string theory required.

Speaker: Dr David Mateos (University of Barcelona)

15:15 Coffee break

15:45 The physics of non-hydrodynamic modes

Speaker: Dr Paul Romatschke (University of Colorado)

Slides Edinburgh18.pptx

Thursday 24 May

09:30 → 12:30 Session 7

09:30 Probing D0-brane Black Holes

Speaker: Dr Evan Berkowitz (FZ Juelich)

Slides 2018-05-24_Edinburgh.pdf

10:45 Coffee break

11:15 Supersymmetry and conformal theories on the lattice, from super Yang-Mills towards super QCD

Speaker: Dr Georg Bergner (Jena University)

12:30 → 14:00 Lunch & discussions

14:00 → 17:00 Session 8

14:00 Holographic Lattice Cosmology

Speaker: Dr Kostas Skenderis (University of Southampton)

Slides Edinburgh2018.pdf

15:15 Coffee break

15:45 Dynamical generation of 4d space-time in nonperturbative superstring theory

We discuss our numerical work on the IKKT matrix model, which was conjectured to be a nonperturbative formulation of superstring theory. In particular, we focus on its Euclidean version, which is speculated to undergo an SSB of SO(10) rotational symmetry, corresponding to the dynamical generation of 4d space-time, due to the effects of the complex fermion determinant. While this issue is difficult to study by conventional Monte Carlo methods because of the sign problem, we show that the complex Langevin method can give clear answers. After discussing important recent developments concerning this method, we present explicit results for some simplified matrix models as well as preliminary results for the original IKKT model. Ref.) JHEP 1802 (2018) 151 [arXiv:1712.07562 [hep-lat]]

Speaker: Dr Jun Nishimura (KEK)

Slides Edinburgh1805v6.pptx