Two Dimensional Quantum (4,4) Null Superstring in de Sitter Space

The (4,4) null superstring equations of motions and constraints on de Sitter space are given by using the harmonic superspace. These are solved explicitly by performing a perturbative expansion of the (4,4) superstring coordinates in powers of c2, the world-sheet speed of light. The analytic expressions of the zeroth and first order solutions are determined. On the other hand, we study the quantization of the (4,4)null superstring in de Sitter space and we describe its superalgebra.