The Off-shell String Effective Action and Black Hole Entropy

          @misc{ scivideos_PIRSA:23040092,
            doi = {},
            url = {http://pirsa.org/23040092},
            author = {Ahmadain, Amir},
            keywords = {Quantum Fields and Strings},
            language = {en},
            title = {The Off-shell String Effective Action and Black Hole Entropy },
            publisher = {Perimeter Institute for Theoretical Physics},
            year = {2023},
            month = {apr},
            note = {PIRSA:23040092 see, \url{https://scivideos.org/PIRSA/23040092}}
          }
          

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