Superstring Perturbation Theory Revisited

TL;DR

This paper revisits perturbative superstring theory to provide a clearer demonstration of gauge invariance, supersymmetry, and infrared behavior of multi-loop amplitudes by analyzing supermoduli space directly.

Contribution

It introduces a simplified, direct approach to superstring perturbation theory by working on supermoduli space, improving understanding of key properties of multi-loop amplitudes.

Findings

Multi-loop amplitudes are gauge-invariant (except known anomalies)

Amplitudes satisfy space-time supersymmetry as expected

Infrared behavior of amplitudes aligns with theoretical predictions

Abstract

Perturbative superstring theory is revisited, with the goal of giving a simpler and more direct demonstration that multi-loop amplitudes are gauge-invariant (apart from known anomalies), satisfy space-time supersymmetry when expected, and have the expected infrared behavior. The main technical tool is to make the whole analysis, including especially those arguments that involve integration by parts, on supermoduli space, rather than after descending to ordinary moduli space.