A Covariant Action with a Constraint and Feynman Rules for Fermions in Open Superstring Field Theory

TL;DR

This paper develops a covariant action with a constraint for fermions in open superstring field theory and derives Feynman rules that reproduce known on-shell amplitudes, advancing computational methods in string theory.

Contribution

It introduces a new covariant fermionic action with a constraint in open superstring field theory and constructs Feynman rules consistent with first quantization results.

Findings

Feynman rules reproduce on-shell tree-level 4-point amplitudes

The action is analogous to type IIB supergravity formulations

Provides a framework for perturbative calculations in superstring theory

Abstract

In a way analogous to type IIB supergravity, we give a covariant action for the fermion field supplemented with a constraint which should be imposed on equations of motion, in Berkovits' open superstring field theory. From this action we construct Feynman rules for computing perturbative amplitudes for fermions. We show that on-shell tree level 4-point amplitudes computed by using these rules coincide with those of the first quantization formalism.