Correlation functions in the D1-D5 orbifold CFT

The D1-D5 system has an orbifold point in its moduli space, at which it may be described by an N = (4, 4) supersymmetric sigma model with target space M-N/S(N) where M is T-4 or K3. In this paper we consider correlation functions involving chiral operators constructed from twist fields: we find explicit expressions for processes involving a twist n operator joining n twist operators of arbitrary twist. These expressions are universal, in that they are independent of the choice of M, and the final results can be expressed in a compact form. We explain how these results are relevant to the black hole microstate programme: one point functions of chiral operators can be used to reconstruct AdS(3) near horizon regions of D1-D5 microstates and to match microstates constructed in supergravity with the CFT.