Tachyon Effective Actions In Open String Theory

Abstract

We argue that the Dirac-Born-Infeld (DBI) action coupled to a tachyon, that is known to reproduce some aspects of open string dynamics, can be obtained from open string theory in a certain limit, which generalizes the limit leading to the usual DBI action. This helps clarify which aspects of the full open string theory are captured by this action.

harvmac, 19 pages; v2 two references added; v3 additional comments and a reference