Please RSVP

Thursday, December 07

Scott Collier (MIT)

Title: 3d quantum gravity and Virasoro TQFT

Abstract: I will discuss the quantization of one of the simplest theories of gravity, three-dimensional Einstein gravity with negative cosmological constant. In particular I will describe a precise reformulation of AdS_3 quantum gravity in terms of a novel topological quantum field theory based on the quantization of the Teichmuller space of Riemann surfaces that we refer to as "Virasoro TQFT." This proposal clarifies the relationship between pure AdS_3 quantum gravity and (two copies of) SL(2,R) Chern-Simons theory, and resolves some well-known issues with this lore. I will argue that moreover this proposal provides a practical framework for the computation of 3d gravity partition functions, and will describe how it elucidates various aspects of the holographic dual.

Tom Hartman (Cornell) visiting 12/7

Title: Averaged null energy and the renormalization group

Abstract: The averaged null energy operator is known to be closely tied to causality, quantum information, and the Regge limit of correlation functions in CFT. I will discuss a new connection between averaged null energy and the monotonicity of the renormalization group, and use the averaged null energy condition (ANEC) to derive the c-theorem in two dimensions and the a-theorem in four dimensions. The derivation is based on contact terms that appear in correlation functions of the null energy operator. Combined with previous results, this also gives a new derivation of the c- and a-theorems from the monotonicity of relative entropy, and hints at a more general role for Lorentzian inversion and light-ray operators in non-conformal QFTs.