U(1) gauge invariance from open string field theory

TL;DR

This paper demonstrates a field redefinition linking string field theory to the world volume action of unstable branes, revealing a string gauge symmetry corresponding to U(1) gauge invariance at a non-linear level.

Contribution

It establishes a field redefinition that relates string field theory variables to brane world volume fields, clarifying the U(1) gauge symmetry in the context of open string field theory.

Findings

Identified a field redefinition connecting string and brane fields.

Revealed a string gauge symmetry corresponding to U(1) gauge invariance.

Analyzed vector fluctuations at the tachyon condensate up to level (4,8).

Abstract

The naive low energy effective action of the tachyon and the U(1) gauge field obtained from string field theory does not correspond to the world volume action of unstable branes in bosonic string theory. We show that there exists a field redefinition which relates the gauge field and the tachyon of the string field theory action to the fields in the world volume action of unstable branes. We identify a string gauge symmetry which corresponds to the U(1) gauge transformation. This is done to the first non-linear order in the fields. We examine the vector fluctuations at the tachyon condensate till level (4,8).