All-loop worldsheet S matrix for AdS_3 x S^3 x T^4

Understand

We obtain the all-loop worldsheet S matrix for fundamental excitations on AdS_3 x S^3 x T^4 by studying the off-shell symmetry algebra of the superspace action in lightcone gauge.

• The massless modes, unaccounted for in earlier works, are automatically included in our treatment.
• Their exact dispersion relation is found to be non-relativistic, of giant-magnon form and their scattering is naturally well-defined.
• This opens the way to a complete investigation of AdS_3/CFT_2 integrability.