Universal moduli-dependent thresholds in Z(2)xZ(2) orbifolds

TL;DR

This paper calculates the universal moduli-dependent threshold corrections to gauge couplings in a specific string orbifold model, showing they lower the unification scale and discussing their relation to other regularization methods.

Contribution

It introduces a method to compute exact string loop corrections in Z2xZ2 orbifolds and determines their impact on gauge coupling unification.

Findings

Threshold corrections decrease the unification scale.

Universal moduli-dependent corrections are explicitly calculated.

Relation to other IR regularization schemes is discussed.

Abstract

In the context of a recently proposed method for computing exactly string loop corrections regularized in the infra-red, we determine and calculate the universal moduli-dependent part of the threshold corrections to the gauge couplings for the symmetric $Z_2\times Z_2$ orbifold model. We show that these corrections decrease the unification scale of the underlying effective field theory. We also comment on the relation between this infra-red regularization scheme and other proposed methods.