<em>R</em>-Symmetries from the Orbifolded Heterotic String

Abstract

We examine the geometric origin of discrete <em>R</em>-symmetries in heterotic orbifold compactifications. By analysing the symmetries of the worldsheet instanton solutions and the underlying geometry, we obtain a scheme that allows us to systematically explore the <em>R</em>-symmetries arising in these compactifications. Applying this scheme to a classification of orbifold geometries, we are able to find all <em>R</em>-symmetries of heterotic orbifolds with Abelian point groups. We show that in the vast majority of cases, the <em>R</em>-symmetries found satisfy anomaly universality constraints, as required in heterotic orbifolds. Then we examine the implications of the presence of these <em>R</em>-symmetries on a class of phenomenologically attractive orbifold compactifications known as the heterotic mini-landscape. We use the technique of Hilbert bases in order to analyse the properties of a vacuum configuration. We find that phenomenologically viable models remain and the main attractive features of the mini-landscape are unaltered.