SL(2, Z) Multiplets of Type II Superstrings in D<10D < 10

It has been shown recently that the toroidally compactified type IIB string effective action possesses an SL(2, R) invariance. Using this symmetry we construct an infinite family of macroscopic string-like solutions permuted by SL(2, Z) group for type II superstrings in $4 \leq D < 10$. These solutions, which formally look very similar to the corresponding solutions in $D = 10$, are characterized by two relatively prime integers corresponding to the `electric' charges associated with the two antisymmetric tensor fields of the strings. Stability of these solutions is discussed briefly in the light of charge conservation and the tension gap equation.Comment: 13 pages, LaTeX, no figures, some statements regarding solutions in D=4 has been corrected, minor typos corrected, more typos corrected, some sentences of clarification have been adde

The Zero Curvature Formulation of TB, sTB Hierarchy and Topological Algebras

A particular dispersive generalization of long water wave equation in $1+1$ dimensions, which is important in the study of matrix models without scaling limit, known as two--Boson (TB) equation, as well as the associated hierarchy has been derived from the zero curvature condition on the gauge group $SL(2,R)\otimes U(1)$. The supersymmetric extension of the two--Boson (sTB) hierarchy has similarly been derived from the zero curvature condition associated with the gauge supergroup $OSp(2|2)$. Topological algebras arise naturally as the second Hamiltonian structure of these classical integrable systems, indicating a close relationship of these models with 2d topological field theories.Comment: 15 pages, plain Latex, no figure