Type I background fields in terms of type IIB ones

Abstract

We choose such boundary conditions for open IIB superstring theory which preserve N=1 SUSY. The explicite solution of the boundary conditions yields effective theory which is symmetric under world-sheet parity transformation $Ω:σ\to-σ$. We recognize effective theory as closed type I superstring theory. Its background fields,beside known $Ω$ even fields of the initial IIB theory, contain improvements quadratic in $Ω$ odd ones.

4 revtex pages, no figures