Recently, a number of exciting connections have been made between large gauge transformations (eg. BMS) and infrared physics (eg. Weinberg's soft graviton theorem). One of the more exciting explorations in this vein was Hawking-Perry-Strominger's (HPS) investigation of the consequences of these new symmetries for black hole physics. I will show very concretely that the Ward identity for the BMS-like large U(1) gauge transformations discussed by HPS fixes the low energy black hole absorption rate for photons. Time permitting, I will discuss broader implications and future extensions.

It is known that thermalization in a CFT corresponds to black hole formation in AdS space. For a system to thermalize it must interact. To address black hole formation in string theory we look for thermalization in the D1D5 CFT which has an AdS dual. Thermalization should occur through interactions caused by twist operators which deform the theory off of its free point. The twist operators can join and unjoin ‘strings’ in the CFT. No clear evidence of thermalization was identified at first order in the twist deformation. We therefore compute interactions at second order in the twist deformation with an initial excitation propagating on one of the strings. We consider transitions of the initial excitation to three lower energy excitations in the final state. This yields preliminary evidence for thermalization.