Nagoya University
Theoretical Elementary Particle Physics Laboratory

Date&Time Wed Apr 28 2021 (10:30 - 11:30)
Masamichi Miyaji
Affiliation UC Berkley
Title Spectrum of End of the World Branes in Holographic BCFTs
Abstract We study overlaps between two regularized boundary states in conformal field theories. Regularized boundary states are dual to end of the world branes in an AdS black hole via the AdS/BCFT. Thus they can be regarded as microstates of a single sided black hole. Owing to the open-closed duality, such an overlap between two different regularized boundary states is exponentially suppressed by h_{AB}^{min}, where h_{AB}^{min} is the lowest energy of open strings which connect two different boundaries A and B. Our gravity dual analysis leads to h_{AB}^{min}=c/24 for a pure AdS 3d gravity. This shows that a holographic boundary state is a random vector among all left-right symmetric states, whose number is given by a square root of the number of all black hole microstates. We also perform a similar computation in higher dimensions, and find that h_{AB}^{min} depends on the tensions of the branes. In our analysis of holographic boundary states, the off diagonal elements of the inner products can be computed directly from on-shell gravity actions, as opposed to earlier calculations of inner products of microstates in two dimensional gravity. We will also discuss some applications of this gapped spectrum.