Towards the All-Loop Worldsheet S Matrix for AdS3× S3× T4.

We obtain the all-loop worldsheet S matrix for fundamental excitations on AdS3× S3× T4 by studying the off-shell symmetry algebra of the superspace action in light cone gauge. The massless modes, unaccounted for in earlier works, are automatically included in our treatment. Their exact dispersion relation is found to be nonrelativistic, of giant-magnon form, and their scattering is naturally well defined. This opens the way to a complete investigation of AdS3/CFT2 integrability. [ABSTRACT FROM AUTHOR]