Massless S matrices for AdS3/CFT2

Abstract

The AdS3/CFT2 correspondence features massless non-relativistic modes on the string worldsheet in lightcone gauge. We study in detail these excitations and highlight how they naturally split between chiral (left-moving) and anti-chiral (right-moving) representations. In light of this split we discuss the constraints on the two-particle worldsheet S matrix imposed by braiding and physical unitarity, parity, time-reversal, and crossing invariance. We also comment on the implication of this split in the mirror kinematics.