Symmetries and Feynman Rules for Ramond Sector in Heterotic String Field Theory

TL;DR

This paper develops new Feynman rules for the Ramond sector in heterotic string field theory, ensuring gauge invariance and reproducing known tree-level amplitudes, advancing the understanding of string interactions.

Contribution

It introduces a prescription for Feynman rules that respect gauge symmetries in heterotic string field theory, extending recent approaches from open superstring theory.

Findings

New Feynman rules reproduce known on-shell amplitudes.

Rules respect all gauge symmetries including constraints.

Extension of superstring Feynman rules to heterotic case.

Abstract

Examining the symmetries of the pseudo-action, we propose a prescription for the new Feynman rules for the Ramond sector of the WZW-like heterotic string field theory. The new rules are an analog of that recently proposed for the open superstring field theory and respect all the gauge symmetries including those provided we impose the constraint after transformation. It is shown that the new rules reproduce the well-known on-shell tree-level amplitudes for four and five external strings including fermions.