We propose exact S-matrices for the AdS3/CFT2 duality between type IIB strings on AdS3×S3×M 4 with M4 = S3×S1 or T 4 and the corresponding two-dimensional conformal field theories. We fix the two-particle S-matrices on the basis of the symmetries su(1|1) and su(1|1)×su(1|1). A crucial justification comes from the derivation of the all-loop Bethe ansatz matching exactly the recent conjecture proposed by Babichenko et al. [J. High Energy Phys. 1003, 058 (2010), arXiv:0912.1723 [hep-th]] and Ohlsson Sax and Stefanski, Jr. [J. High Energy Phys. 1108, 029 (2011), arXiv:1106.2558 [hep-th]].
- Bethe ansatz