Open String Tachyon in Supergravity Solution

TL;DR

This paper investigates the supergravity description of tachyon condensation in D-ar{D} brane systems, identifying the relevant parameters and their physical interpretations, and comparing solutions with string theory expectations.

Contribution

It clarifies the role of parameters in supergravity solutions related to tachyon condensation and shows that one parameter does not correspond to the tachyon vev.

Findings

The three-parameter solution includes extremal black p-branes as a limit.

Fixing one parameter (c_1) is necessary to match string theory boundary states.

The parameter c_1 does not represent the tachyon vev in the supergravity solution.

Abstract

We study the tachyon condensation of the D-\bar{D}-brane system with a constant tachyon vev in the context of classical solutions of the Type II supergravity. We find that the general solution with the symmetry ISO(1,p)xSO(9-p) (the three-parameter solution) includes the extremal black p-brane solution as an appropriate limit of the solution with fixing one of the three parameters (c_1). Furthermore, we compare the long distance behavior of the solution with the massless modes of the closed strings from the boundary state of the D-\bar{D}-brane system with a constant tachyon vev. We find that we must fix c_1 to zero and the only two parameters are needed to express the tachyon condensation of the D\={D}-brane system. This means that the parameter $c_1$ does not correspond to the tachyon vev of the D\={D}-brane system.