Tachyon condensation and universality of DBI action

TL;DR

This paper demonstrates that the low-energy effective action for fluctuations around a tachyonic soliton, representing a D-brane, universally reduces to the Dirac-Born-Infeld action, regardless of specific tachyon models.

Contribution

It establishes the universality of the DBI action as the effective description of D-brane fluctuations in tachyon condensation scenarios.

Findings

The effective action matches the DBI form for massless fluctuations.

Transverse oscillations are identified as collective coordinates.

Universality holds across models with similar open string sigma model structure.

Abstract

We show that a low-energy action for massless fluctuations around a tachyonic soliton background representing a codimension one D-brane coincides with the Dirac-Born-Infeld action. The scalar modes which describe transverse oscillations of the D-brane are translational collective coordinates of the soliton. The appearance of the DBI action is a universal feature independent of details of a tachyon effective action, provided it has the structure implied by the open string sigma model partition function.