Symmetries and Feynman rules for the Ramond sector in heterotic string field theory

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 those recently proposed for the open superstring field theory and respect all the gauge symmetries, including when 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.