An alternative approach to tachyon cosmology

TL;DR

This paper introduces an alternative action for open string tachyon dynamics on non-BPS D3-branes, incorporating world-volume gravity, and explores its cosmological implications including exponential expansion and bouncing universes.

Contribution

It presents a new tachyon action with dynamical gravity coupling, providing novel cosmological solutions and insights into tachyon condensation effects.

Findings

Exponential expansion with positive cosmological constant.

Bouncing universe solutions in anti de-Sitter scenarios.

Tachyon condensation leads to late-time inflation.

Abstract

In this note we propose the use of an alternate action for the open string tachyon on a non-BPS $D3$-brane. At the classical level this action is precisely equivalent to the more commonly used DBI action, but involves an additional coupling to dynamical world-volume gravity. We find that, for a FRW metric, exponential expansion occurs provided that the cosmological constant is positive. For anti de-Sitter solutions we find a periodically bouncing universe, and there are no accelerating trajectories for a theory with no cosmological constant. In specific cases the acceleration is terminated by the condensation of the open string tachyon, leading to a canonical inflationary trajectory at late times.