Universality of radiative corrections to gauge couplings for strings with spontaneously broken supersymmetry

TL;DR

This paper reviews recent calculations of radiative corrections to gauge couplings in four-dimensional heterotic string models with spontaneously broken supersymmetry, highlighting the universal and exactly computable nature of gauge threshold differences.

Contribution

It demonstrates that despite supersymmetry breaking, the difference in gauge thresholds remains universal and exactly computable, extending previous BPS protection results.

Findings

Gauge threshold differences are universal and exactly computable.

Radiative corrections include contributions from non-BPS sectors.

Spontaneous supersymmetry breaking does not destroy the universality of gauge coupling differences.

Abstract

I review recent work on computing radiative corrections to non-abelian gauge couplings in four-dimensional heterotic vacua with spontaneously broken supersymmetry. The prototype models can be considered as K3 surfaces with additional Scherk-Schwarz fluxes inducing the spontaneous $\mathcal{N}=2 \to \mathcal{N}=0$ breaking. Remarkably, although the gauge thresholds are no longer BPS protected and receive contributions also from the excitations of the RNS sector, their difference is still exactly computable and universal. Based on a talk presented at the DISCRETE 2014 conference at King's College London.