String amplitudes in the Hpp-wave limit of AdS3 × S3

We compute string amplitudes on pp-waves supported by NS-NS 3-form fluxes and arising in the Penrose limit of AdS₃ × S³ × Script M. We clarify the role of the non-chiral accidental SU(2) symmetry of the background. We comment on the extension of our results to the superstring and propose a holographic formula in the BMN limit of the AdS₃/CFT₂ correspondence valid for any correlator.