Higher-Derivative Gravity in String Theory

TL;DR

This paper computes higher-derivative curvature terms in the heterotic string effective action at genus 0 and 1, using on-shell superstring amplitudes, and discusses moduli-dependent gravitational threshold corrections.

Contribution

It explicitly derives the structure of curvature-squared terms in the heterotic string effective action at low genus levels using amplitude calculations.

Findings

Derived explicit form of curvature-squared terms at genus 0 and 1.

Analyzed moduli dependence of gravitational threshold corrections.

Provided insights into the structure of higher-derivative corrections in string theory.

Abstract

We explicitly extract the structure of higher-derivative curvature-squared terms at genus 0 and 1 in the d=4 heterotic string effective action compactified on symmetric orbifolds by computing on-shell S-matrix superstring amplitudes. In particular, this is done within the context of calculating the graviton 4-point amplitude. We also discuss the moduli-dependent gravitational threshold corrections to the coupling associated with the CP even quadratic curvature terms.