On the Cosmological Relevance of the Tachyon

TL;DR

This paper investigates the effective action of the tachyon field on D-branes in string theory, exploring its cosmological implications, including its potential to act as a cosmological constant or quintessence.

Contribution

It introduces a corrected Born-Infeld type Lagrangian for the tachyon field and analyzes its cosmological relevance in both bosonic and superstring theories.

Findings

The tachyon's kinetic term requires correction to the standard Lagrangian.

The rolling tachyon can mimic a cosmological constant under certain conditions.

Tachyon dynamics differ from traditional quintessence models.

Abstract

We analyse of the effective action of the tachyon field on a D-brane, of both bosonic as well as superstring theory. We find that the non-standard kinetic term of the tachyon field requires a correction to the Born-Infeld type Lagrangian. The cosmological significance of the resulting dynamics is explored. We also examine if the rolling tachyon can provide an effective cosmological constant and contrast its behaviour with quintessence.