Closed String Amplitudes in Open String Field Theory

TL;DR

This paper demonstrates that gauge invariant operators in open string field theory reproduce known closed string scattering amplitudes, confirming their physical relevance and consistency.

Contribution

It provides a detailed calculation of closed string amplitudes within open string field theory using oscillator and conformal mapping methods, showing agreement with standard results.

Findings

The two closed string tachyon amplitude matches the disc amplitude.

Gauge invariant operators correctly reproduce closed string scattering.

The methods confirm the consistency of open string field theory with closed string physics.

Abstract

We investigate gauge invariant operators corresponding to on-shell closed string states in open string field theory. Using both oscillator representation and conformal mapping techniques, we calculate a two closed string tachyon amplitude that connects two gauge invariant operators by an open string propagator.We find that this amplitude is in a complete agreement with the usual disc amplitude.