String loop threshold corrections for N=1 generalized Coxeter orbifolds Original Research Article

We discuss the calculation of threshold corrections to gauge coupling constants for the, only, non-decomposable class of abelian (2,2) symmetric N=1 four dimensional heterotic orbifold models, where the internal twist is realized as a generalized Coxeter automorphism. The latter orbifold was singled out by earlier work as the only N=1 heterotic ZN orbifold that satisfy the phenomenological criteria of correct minimal gauge coupling unification and cancellation of target space modular anomalies.