Observables of String Field Theory

TL;DR

This paper explores gauge invariant operators in open string field theory, establishing a correspondence with on-shell closed strings and analyzing their implications for scattering amplitudes and vacuum string field theory.

Contribution

It provides a detailed proof of gauge invariance and interprets correlation functions as on-shell closed string scattering amplitudes.

Findings

Gauge invariant operators correspond to on-shell closed strings

Correlation functions relate to closed string scattering amplitudes

Implications for vacuum string field theory are discussed

Abstract

We study gauge invariant operators of open string field theory and find a precise correspondence with on-shell closed strings. We provide a detailed proof of the gauge invariance of the operators and a heuristic interpretation of their correlation functions in terms of on-shell scattering amplitudes of closed strings. We also comment on the implications of these operators to vacuum string field theory.