Superconformal Field Theory with Boundary: Fermionic Model

Fermionic model of Superconformal field theory with boundary is considered. There were written the ''boundary'' Ward Identity for this theory and also constructed boundary states for fermionic and spin models. For this model were derived ''bootstrap'' equations for boundary structure constants.Comment: 12 page

On Non-Critical Superstring/Black Hole Transition

An interesting case of string/black hole transition occurs in two-dimensional non-critical string theory dressed with a compact CFT. In these models the high energy densities of states of perturbative strings and black holes have the same leading behavior when the Hawking temperature of the black hole is equal to the Hagedorn temperature of perturbative strings. We compare the first subleading terms in the black hole and closed string entropies in this setting and argue that the entropy interpolates between these expressions as the energy is varied. We compute the subleading correction to the black hole entropy for a specific simple model.Comment: 10 pages; harvma

The Ground Ring of N=2 Minimal String Theory

We study the \NN=2 string theory or the \NN=4 topological string on the deformed CHS background. That is, we consider the \NN=2 minimal model coupled to the \NN=2 Liouville theory. This model describes holographically the topological sector of Little String Theory. We use degenerate vectors of the respective \NN=2 Verma modules to find the set of BRST cohomologies at ghost number zero--the ground ring, and exhibit its structure. Physical operators at ghost number one constitute a module of the ground ring, so the latter can be used to constrain the S-matrix of the theory. We also comment on the inequivalence of BRST cohomologies of the \NN=2 string theory in different pictures.Comment: 25 pages, latex, small correction