A tachyon lump in closed string field theory

TL;DR

This paper constructs a codimension one lump solution in closed bosonic string field theory, analyzing the behavior of the tachyon, ghost dilaton, and metric fluctuation, and providing insights into their profiles and interactions.

Contribution

It introduces a new lump solution in closed string field theory considering vertices up to quartic order, including key fields, and explains the ghost dilaton's behavior with a simple model.

Findings

The tachyon profile forms a clear lump.

The ghost dilaton remains roughly constant transverse to the lump.

The behavior aligns with predictions from a simple theoretical model.

Abstract

We find a codimension one lump solution of closed bosonic string field theory. We consider vertices up to quartic order and include in the string field the tachyon, the ghost dilaton, and a metric fluctuation. While the tachyon profile clearly is that of a lump, we observe that the ghost dilaton is roughly constant in the direction transverse to the lump, equal to the value it takes in the nonperturbative tachyon vacuum. We explain, with a simple model, why this should be expected.