Chiral shift symmetries as an infinite tower of subleading super-shift symmetries

Abstract

Chiral shift symmetries of the massless free bosons in two dimensions are global symmetries that are somewhat similar to asymptotic symmetries. They are most transparent in double-null coordinates where they are parametrized by two functions of one variable. In BMS-type coordinates, half of them appear as an infinite tower of sub-leading super-shift symmetries.