Interpolating between open and closed strings - a BSFT approach

TL;DR

This paper explores how boundary string field theory can interpolate between open and closed string states, providing a framework for understanding the transformation at the tachyonic vacuum.

Contribution

It demonstrates a method within boundary string field theory to smoothly transition from open string configurations to closed string states.

Findings

Open strings can be transformed into closed strings within BSFT.

Boundary states can interpolate between open and closed string vacua.

Correlation functions match those of closed strings at the transition.

Abstract

We address the conjecture that at the tachyonic vacuum open strings get transformed into closed strings. We show that it is possible in the context of boundary string field theory to interpolate between the conventional open string theory, characterized by having the D25 brane as the boundary state, and an off-shell (open) string theory where the boundary state is identified with the closed string vacuum, where holomorphic and antiholomorphic modes decouple and where bulk vertex operator correlation functions are identical to those of the closed string.