Tachyon Condensation and Universal Solutions in String Field Theory

TL;DR

This paper studies a non-perturbative vacuum in open string field theory, showing that universal solutions behave as the tachyon vacuum at the boundary of parameter space, with vacuum energy canceling D-brane tension.

Contribution

It provides numerical evidence supporting the conjecture that universal solutions are tachyon vacua at the boundary, using level-truncation analysis up to level (6,18).

Findings

Vacuum energy cancels D-brane tension at higher levels.

Universal solutions are pure gauge except at boundary.

Non-perturbative vacuum disappears at parameter space boundary.

Abstract

We investigate a non-perturbative vacuum in open string field theory expanded around the analytic classical solution which has been found in the universal Fock space generated by matter Virasoro generators and ghost oscillators. We carry out level-truncation analyses up to level (6,18) in the theory around one-parameter families of the solution. We observe that the value of the vacuum energy cancels the D-brane tension as the approximation level is increased, but this non-perturbative vacuum disappears at the boundary of the parameter space. These results provide strong evidence for the conjecture that, although the universal solutions are pure gauge in almost all the parameter space, they are regarded as the tachyon vacuum solution at the boundary.