Orbifold Compactifications of Type IIB and Supersymmetry Breaking
Summary
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.