This week

Monday (03 Feb)

Lonti: An introduction to the black hole information paradox (3/4)

Regular Seminar Tarek Anous (QMUL)

at:
10:30 Other
room LIMS
abstract:

This course will give a technical introduction to the black hole information paradox (BHIP). In the first lecture, we will begin with a review of quantum path integrals, both in Lorentzian and in Euclidean signature. We will review the Euclidean path integral connection with statistical mechanics and thermodynamics while also reviewing the derivation of the first law of thermodynamics in standard equilibrium statistical mechanics. We will then introduce the laws of black hole thermodynamics, and study them in particular examples. The second lecture will be devoted to the Unruh effect. We will study free quantum field theory in Rindler space, which, locally, is the spacetime observed by a uniformly accelerated observer. We will derive that this observer measures a temperature related to the observer proper acceleration. The third lecture will be devoted to classical and quantum information theory including notions of conditional probability, mutual information, and entropy inequalities, in settings with finite numbers of degrees of freedom. We will also introduce the Page curve and its significance. Finally, in the fourth lecture we will set up a toy model of the BHIP in Anti de Sitter space (AdS). Because AdS is believed to have a dual description as a conformal quantum field theory, we will use this duality to our advantage. We end with a broad discussion synthesizing what we have learned, and what is left to understand.

Wednesday (05 Feb)

The complex Liouville string

Triangular Seminar Beatrix Muehlmann (IAS)

at:
15:00 QMUL
room Peoples Palace 1
abstract:

I will introduce a new 2d gravity/matrix integral duality. The bulk theory is a two-dimensional string theory defined by coupling two copies of Liouville CFT with central charges c = 13 \pm is on the worldsheet. We call this string theory the complex Liouville string. I will argue that the complex Liouville string admits a dual description in terms of a double-scaled two-matrix integral. The string amplitudes, which are the main observables of the complex Liouville string, can be interpreted as cosmological correlators of massive particles, integrated over the metric at future infinity of dS3 to define gauge invariant observables. Furthermore we obtain evidence that the dS3 Gibbons-Hawking entropy can be reproduced exactly by counting the degrees of freedom in the dual matrix integral.

Fuzzy sphere regularization of 3D CFTs

Triangular Seminar Yin-Chen He (Stony Brook University)

at:
16:30 QMUL
room Peoples Palace 1
abstract:

Conformal Field Theory (CFT) represents a class of quantum field theories that have profound applications across various physics domains, from critical phenomena in statistical mechanics to quantum matter, quantum gravity, and string theory. In this talk, I will introduce our recently proposed fuzzy (non-commutative) sphere regularization scheme, a method that addresses and offers a solution to the longstanding need for a non-perturbative approach to 3D CFTs. I will first elucidate its fundamental concepts and then dive into illustrative examples, including the 3D Ising transition, conformal defects, and critical gauge theories. Importantly, I will showcase that this scheme is not only potent--revealing a wealth of universal data on 3D CFTs otherwise inaccessible through existing methods--but also efficient, as the necessary computations can be performed on a laptop within an hour. Our innovative scheme not only heralds a new era for the study of CFTs but also hints at a profound interplay between non-commutative geometry and both CFTs and QFTs at large.