Double-Copy Structure of One-Loop Open-String Amplitudes

TL;DR

This paper uncovers a new double-copy structure in one-loop open-string amplitudes, linking gauge theories and gravity through symmetric integrand formulations involving elliptic functions.

Contribution

It introduces a novel double-copy framework for one-loop open-string amplitudes using generalized elliptic integrands and kinematic factors.

Findings

Reveals a symmetric form of integrands involving elliptic functions.

Maps open-string correlators to gravitational matrix elements of R^4.

Provides evidence for a double-copy structure at one-loop level.

Abstract

In this Letter, we provide evidence for a new double-copy structure in one-loop amplitudes of the open superstring. Their integrands with respect to the moduli space of genus-one surfaces are cast into a form where gauge-invariant kinematic factors and certain functions of the punctures -- so-called generalized elliptic integrands -- enter on completely symmetric footing. In particular, replacing the generalized elliptic integrands by a second copy of kinematic factors maps one-loop open-string correlators to gravitational matrix elements of the higher-curvature operator R^4.