Regularization of identity based solution in string field theory

TL;DR

This paper shows that an Erler-Schnabl type solution in cubic string field theory can be viewed as a gauge invariant regularization of an identity-based solution, with gauge invariance confirmed for key physical quantities.

Contribution

It introduces a gauge invariant regularization method for identity-based solutions in string field theory using an interpolating solution.

Findings

Classical action is gauge invariant.

Closed string tadpole remains gauge invariant.

The interpolating solution smoothly connects identity-based and Erler-Schnabl solutions.

Abstract

We demonstrate that an Erler-Schnabl type solution in cubic string field theory can be naturally interpreted as a gauge invariant regularization of an identity based solution. We consider a solution which interpolates between an identity based solution and ordinary Erler-Schnabl one. Two gauge invariant quantities, the classical action and the closed string tadpole, are evaluated for finite value of the gauge parameter. It is explicitly checked that both of them are independent of the gauge parameter.