The paper “S-matrix for the massive and massless modes of the AdS_2 x S^2 superstring“, co-authored by Ben Hoare (Humboldt University), Antonio Pittelli, and Alessandro Torrielli, has been accepted for publication in the Journal of High Energy Physics.  In the paper they derive the exact S-matrix for the integrable system associated to light-cone gauge string theory on AdS_2 x S^2 x T^6.  The final form preprint can be found on the ArXiv here.