Heterotic and bosonic string amplitudes via field theory

TL;DR

This paper extends double-copy constructions to heterotic and bosonic string theories, linking string amplitudes to a specific $ ext{D}_ ext{mu}F^{ ext{mu} u}$-based field theory and scalar integrals, revealing new amplitude relations.

Contribution

It identifies a novel double-copy framework for heterotic and bosonic strings using an $ ext{alpha'}$-dependent field theory with operators like $(D_ ext{mu}F^{ ext{mu} u})^2$, connecting to conformal supergravity.

Findings

Established double-copy structures for heterotic and bosonic strings.

Derived new amplitude relations for gauge-gravity theories.

Explored the $ ext{alpha'} ightarrow ext{infinity}$ limit and its implications.

Abstract

Previous work has shown that massless tree amplitudes of the type I and IIA/B superstrings can be dramatically simplified by expressing them as double copies between field-theory amplitudes and scalar disk/sphere integrals, the latter containing all the $\alpha'$-corrections. In this work, we pinpoint similar double-copy constructions for the heterotic and bosonic string theories using an $\alpha'$-dependent field theory and the same disk/sphere integrals. Surprisingly, this field theory, built out of dimension-six operators such as $(D_\mu F^{\mu \nu})^2$, has previously appeared in the double-copy construction of conformal supergravity. We elaborate on the $\alpha' \rightarrow \infty$ limit in this picture and derive new amplitude relations for various gauge-gravity theories from those of the heterotic string.