Inhomogeneous Fragmentation of the Rolling Tachyon

TL;DR

This paper analyzes the inhomogeneous decay of the rolling tachyon in string theory, revealing a web-like energy density fragmentation and a dual particle mechanics picture with implications for inflationary models.

Contribution

It provides an analytic asymptotic solution for inhomogeneous tachyon dynamics and introduces a dual particle mechanics perspective for arbitrary dimensions.

Findings

Tachyon energy density forms a web-like network during decay

The tachyon field dynamics can be described by free streaming of massive particles

Implications for inflationary models with decaying tachyons are discussed

Abstract

Dirac-Born-Infeld type effective actions reproduce many aspects of string theory classical tachyon dynamics of unstable Dp-branes. The inhomogeneous tachyon field rolling from the top of its potential forms topological defects of lower codimensions. In between them, as we show, the tachyon energy density fragments into a p-dimensional web-like high density network evolving with time. We present an analytic asymptotic series solution of the non-linear equations for the inhomogeneous tachyon and its stress energy. The generic solution for a tachyon field with a runaway potential in arbitrary dimensions is described by the free streaming of noninteracting massive particles whose initial velocities are defined by the gradients of the initial tachyon profile. Thus, relativistic particle mechanics is a dual picture of the tachyon field effective action. Implications of this picture for inflationary models with a decaying tachyon field are discussed.