One-loop string corrections to the effective field theory

We calculate the parity-conserving one-loop string corrections to the bosonic part of the 10-dimensional effective field theory for the heterotic string. There is no renormalization of the Chamseddine-Chapline-Manton supergravity action, but terms of fourth order in the curvature tensors are generated. Most of these are of the same forms as those found at the tree level of the string topological expansion, such as (TrR2)2, (TrR2)(TrF2) and (TrF2)2. However, we also find a non-zero Tr(F4) coupling which was not present at the tree level. We comment on the phenomenological implications of these results, which include absences of renormalization of the Kaehler metric and of the gauge kinetic function of the effective field theory in four dimensions after compactification, and a modification of the classical equations to be obeyed by the manifold of compactification. (orig.)