Video URL
https://pirsa.org/23040092The Off-shell String Effective Action and Black Hole Entropy
Amr Ahmadain University of Cambridge
Abstract
Taking string theory off shell requires breaking Weyl invariance on the worldsheet, i.e. the worldsheet theory is now a QFT instead of a CFT. I will explain Tseytlin’s first-quantized approach to taking the worldsheet theory off-shell in a consistent manner, with a particular emphasis on the subtleties involved in calculating the sphere amplitude. This approach allows for the derivation of a classical string action which gives rise to the correct equations of motion and S-matrix, to all orders in perturbation theory.
I'll also explain the underlying conceptual structure of the Susskind and Uglum black hole entropy argument. There I will show explicitly how the classical (tree-level) effective action and entropy S = A/4G_N may be calculated from the sphere diagrams.
Time permitting, I will discuss ongoing efforts to derive the Ryu-Takayanagi formula in string theory.
Based on arXiv:2211.08607 and arXiv:2211.16448.
Zoom link: https://pitp.zoom.us/j/93668017324?pwd=K2pxZEhjalRTWkVVbVRESCtRVDFmUT09