Notes on S-Matrix of Non-critical N=2 String

In this paper we discuss the scattering S-matrix of non-critical N=2 string at tree level. First we consider the \hat{c}<1 string defined by combining the N=2 time-like linear dilaton SCFT with the N=2 Liouville theory. We compute three particle scattering amplitudes explicitly and find that they are actually vanishing. We also find an evidence that this is true for higher amplitudes. Next we analyze another \hat{c}<1 string obtained from the N=2 time-like Liouville theory, which is closely related to the N=2 minimal string. In this case, we find a non-trivial expression for the three point functions. When we consider only chiral primaries, the amplitudes are very similar to those in the (1,n) non-critical bosonic string.Comment: 27 pages, harvmac, section 5 modified: a relation to (1,n) non-critical bosonic string adde

Correspondence Principle for Black Holes in Plane Waves

We compare the entropy as a function of energy of excited strings and black strings in an asymptotically plane wave background at the level of the correspondence principle. For the plane wave supported by the NSNS 3-form flux, neither the entropy formula nor the cross-over scale is affected by the presence of the flux and the correspondence is found to hold. For the plane wave supported by the RR 3-form flux, both the entropy and the cross-over point are modified, but the correspondence is still found to hold.Comment: 20 pages, References Adde

Topological String on OSP(1|2)/U(1)

We propose an equivalence between topological string on OSP(1|2)/U(1) and \hat{c} \leq 1 superstring with N=1 world-sheet supersymmetry. We examine this by employing a free field representation of OSP(1|2) WZNW model and find an agreement on the spectrum. We also analyze this proposal at the level of scattering amplitudes by applying a map between correlation functions of OSP(1|2) WZNW model and those of N=1 Liouville theory.Comment: 25 pages, refereces adde