Universality of gauge thresholds in non-supersymmetric heterotic vacua

Carlo Angelantonj,Ioannis Florakis,Mirian Tsulaia

doi:10.1016/j.physletb.2014.08.001

Universality of gauge thresholds in non-supersymmetric heterotic vacua

Carlo Angelantonj, Ioannis Florakis + Show 1 more

Open Access

https://doi.org/10.1016/j.physletb.2014.08.001

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Abstract

We compute one-loop threshold corrections to non-abelian gauge couplings in four-dimensional heterotic vacua with spontaneously broken N=2→N=0 supersymmetry, obtained as Scherk–Schwarz reductions of six-dimensional K3 compactifications. As expected, the gauge thresholds are no-longer BPS protected, and receive contributions also from the excitations of the RNS sector. Remarkably, the difference of thresholds for non-abelian gauge couplings is BPS saturated and exhibits a universal behaviour independently of the orbifold realisation of K3. Moreover, the thresholds and their difference develop infra-red logarithmic singularities whenever charged BPS-like states, originating from the twisted RNS sector, become massless at special loci in the classical moduli space.

Highlights

In the last decades we have witnessed a tremendous progress in understanding the structure of supersymmetric vacua in String Theory and M/F-theory
Supersymmetry breaking in String Theory remains a compelling open problem that string phenomenology aspires to address
A fully-fledged approach to spontaneous supersymmetry breaking in String Theory, that admits an exactly solvable world-sheet description, is the stringy realisation [1,2,3,4] of the Scherk-Schwarz mechanism [5, 6], via special freely-acting orbifolds

Summary

Introduction

In the last decades we have witnessed a tremendous progress in understanding the structure of supersymmetric vacua in String Theory and M/F-theory. The emergence of one-loop tadpoles for massless states does not impinge on the validity of the one-loop analysis, it makes the incorporation of higher loops problematic, unless the back-reaction on the classical vacuum is properly taken into account [12, 13] For this reason, we address in this letter the problem of computing one-loop threshold corrections to gauge couplings in a class of four-dimensional heterotic vacua with spontaneously broken supersymmetry, that can be built as K3 reductions of the SO(16) × SO(16) construction of [14] in terms of freely-acting orbifolds.

Heterotic vacuum with spontaneous supersymmetry breaking

One-loop thresholds for non-abelian gauge couplings

R21 and