On Chiral Splitting and the Ambitwistor String

TL;DR

This paper demonstrates that superstring scattering amplitudes can be holomorphically split into chiral parts and that these match ambitwistor string computations in the tensionless limit, addressing higher-genus subtleties.

Contribution

It establishes the equivalence of superstring and ambitwistor string chiral integrands at higher genus, including resolution of supermoduli space subtleties.

Findings

Superstring amplitudes holomorphically split into chiral integrands.

Chiral integrands match ambitwistor string results in the zero tension limit.

Addresses higher-genus supermoduli space issues.

Abstract

Scattering amplitudes computed by superstring perturbation theory are known to holomorphically split into chiral half integrands at fixed internal loop momentum. It is established by direct computation that upon reduction to the ordinary moduli space, the chiral half integrands of the superstring match those computed by the ambitwistor string in the limit of zero tension ($\alpha'\rightarrow\infty$). Subtleties that arise at higher genus due to the nonprojectedness of the supermoduli space are considered and arguments as to their resolution are furnished.