Orbifold Compactifications of Type IIB and Supersymmetry Breaking

Abstract

We study orbifold compactifications of type IIB string theory. In particular, we construct orbifolds of the form (S^1 × T^4)/Z_p preserving partial or no supersymmetry, giving rise to classical 5D Minkowski vacua. We demonstrate that these orbifold constructions are the lifts to string theory of type IIB supergravity reduced on a T^4 and furthermore reduced on a circle with a Scherk-Schwarz twist. We also study the vacua of the resulting theories and investigate if a one-loop cosmological constant can be generated, both from the supergravity and from the string-theoretic point of view.