Heterotic moduli, the double extension and the alpha'^2 metric

Abstract

We compute the heterotic moduli-space metric through $α'^2$ for backgrounds admitting a smooth $α'\to0$ limit. The Kaehler potential is unchanged when written in an appropriate field basis suggested by the ten-dimensional supersymmetry equations, while the metric receives $α'^2$ corrections. We discuss this and clarify the roles of the extension bundle, F-terms, the D-terms and the string-derived moduli space metric.