IPM Calendar 
Tuesday 7 July 2020   Today  
Events for day: Tuesday 7 July 2020    
           14:00 - 15:00     Weekly Seminar
HEPCo Group
T-Witts from the horizon


Expanding around null hypersurfaces, such as generic Kerr black hole horizons, using co-rotating Kruskal--Israel-like coordinates we study the associated surface charges, their symmetries and the corresponding phase space within Einstein gravity. Our surface charges are not integrable in general. Their integrable part generates an algebra including superrotations and a BMS$_3$--type algebra that we dub ``T-Witt algebra''. The non-integrable part accounts for the flux passing through the null hypersurface. We put our results in the context of earlier constructions of near horizon symmetries, soft hair and of the program to semi-classically ide ...