Tuesday, May 27th, 2025
Program: Black Hole physics
Time: 10:45 AM - 12:00 PM
Location: SCGP 313
Title: Universal thermalization dynamics in (1+1)d QFTs
Speaker: Richard Davison
Abstract: Interacting quantum field theories typically thermalize, leading to the emergence of hydrodynamics at late times. I will talk about (1+1)d QFTs at high temperatures, where the proximity to a CFT results in parametrically slow thermalization, with much of the associated dynamics tractable. I will first explain how the UV effective theory – conformal perturbation theory – breaks down at late times giving room for hydrodynamics to emerge. Specialising to the case of large central charge, I will then argue that the IR effective theory – hydrodynamics -- has universal transport coefficients and use this to show that it breaks down at early times due to the existence of thermal CFT excitations. The timescales at which the two effective theories break down agree.
Title: Universal thermalization dynamics in (1+1)d QFTs
Speaker: Richard Davison
Abstract: Interacting quantum field theories typically thermalize, leading to the emergence of hydrodynamics at late times. I will talk about (1+1)d QFTs at high temperatures, where the proximity to a CFT results in parametrically slow thermalization, with much of the associated dynamics tractable. I will first explain how the UV effective theory – conformal perturbation theory – breaks down at late times giving room for hydrodynamics to emerge. Specialising to the case of large central charge, I will then argue that the IR effective theory – hydrodynamics -- has universal transport coefficients and use this to show that it breaks down at early times due to the existence of thermal CFT excitations. The timescales at which the two effective theories break down agree.
Wednesday, May 28th, 2025
Program: Black Hole physics
Time: 10:45 AM - 12:00 PM
Location: SCGP 313
Title: The AdS/CFT correspondence to all order
Speaker: Kostas Skenderis
Abstract: We show that AdSd+1 gravity is a d-dimensional CFT by showing that the AdS amplitudes to all orders in bulk perturbation theory satisfy the appropriate CFTd Ward identities. We explain how to renormalize UV and IR divergences in AdS and how these are related to renormalization in CFT and illustrate the renormalization via loop computations.
Title: The AdS/CFT correspondence to all order
Speaker: Kostas Skenderis
Abstract: We show that AdSd+1 gravity is a d-dimensional CFT by showing that the AdS amplitudes to all orders in bulk perturbation theory satisfy the appropriate CFTd Ward identities. We explain how to renormalize UV and IR divergences in AdS and how these are related to renormalization in CFT and illustrate the renormalization via loop computations.
Thursday, May 29th, 2025
Program: Black Hole physics
Time: 10:45 AM - 12:00 PM
Location: SCGP 313
Title: Bootstrapping Thermal CFTs
Speaker: Elli Pomoni
Abstract: In this talk, we explore the structure and solution of thermal conformal field theories (CFTs) using the conformal bootstrap approach. At finite temperature, the role of crossing symmetry is played by the Kubo-Martin Schwinger (KMS) condition, which imposes periodicity on thermal correlation functions. We present two methods for solving the resulting KMS sum rules for thermal one-point functions, assuming knowledge of the zero-temperature CFT data. The first is a numerical method that incorporates the asymptotic operator product expansion (OPE) density of heavy operators, derived using Tauberian theorems. The second is an analytical approach based on dispersion relations. We benchmark both methods against known results in free theories and two dimensional CFTs, and subsequently apply them to O(N) models for N=1,2,3, as well as in the large-N limit.
Title: Bootstrapping Thermal CFTs
Speaker: Elli Pomoni
Abstract: In this talk, we explore the structure and solution of thermal conformal field theories (CFTs) using the conformal bootstrap approach. At finite temperature, the role of crossing symmetry is played by the Kubo-Martin Schwinger (KMS) condition, which imposes periodicity on thermal correlation functions. We present two methods for solving the resulting KMS sum rules for thermal one-point functions, assuming knowledge of the zero-temperature CFT data. The first is a numerical method that incorporates the asymptotic operator product expansion (OPE) density of heavy operators, derived using Tauberian theorems. The second is an analytical approach based on dispersion relations. We benchmark both methods against known results in free theories and two dimensional CFTs, and subsequently apply them to O(N) models for N=1,2,3, as well as in the large-N limit.
Friday, May 30th, 2025
Program: Black Hole physics
Time: 10:45 AM - 12:00 PM
Location: SCGP 313
Title: Ringdown at finite coupling
Speaker: Matthew Dodelson
Abstract: Thermal correlators in large N systems equilibrate at late times, but the precise late-time behavior is unknown away from holographic and free field limits. In this talk I will analyze this problem in the case of the SYK model away from the low-temperature limit. Even at infinite temperatures, the correlator decomposes into a sum over quasinormal modes, and I will explain how to think about the result in terms of a stringy black hole. I will also briefly discuss the example of cellular automata, and explain several methods for addressing the problem more generally.
Title: Ringdown at finite coupling
Speaker: Matthew Dodelson
Abstract: Thermal correlators in large N systems equilibrate at late times, but the precise late-time behavior is unknown away from holographic and free field limits. In this talk I will analyze this problem in the case of the SYK model away from the low-temperature limit. Even at infinite temperatures, the correlator decomposes into a sum over quasinormal modes, and I will explain how to think about the result in terms of a stringy black hole. I will also briefly discuss the example of cellular automata, and explain several methods for addressing the problem more generally.