Hybrid Superstring on AdS_3 and Space-Time Superconformal Symmetry
  Using a hybrid formalism, superstrings on AdS(3) x S(1) are studied in a manifestly supersymmetric manner. The world-sheet fields in this description including superspace coordinates are obtained through a field redefinition from the corresponding ones in the RNS formalism. The physical states are defined with the BRST cohomology as an N=4 topological string theory. The physical spectra for some lower mass levels are investigated. We identify two series of the space-time chiral primaries which have already been obtained from the analysis in the RNS formalism. We find that they are described by the chiral and the vector supermultiplets, but the on-shell physical structure of the latter depends on whether it is massive or massless. The spece-time supersymmetry on this background is extended to the boundary N=2 uperconformal symmetry. We explicitly construct its generators and study how they act on specific supermultiplets. 
Hiroshi Kunitomo