Cosmological Evolution of the Rolling Tachyon

TL;DR

This paper explores how a tachyon field influences the universe's expansion, showing that its evolution can lead to different cosmological outcomes, including static or Milne-type spacetimes, depending on initial conditions.

Contribution

It introduces a coupling of a tachyon effective field theory with Einstein gravity to analyze cosmological evolution and outcomes.

Findings

Universe expands as tachyon rolls down its potential.

Final spacetime can be static or Milne model depending on initial conditions.

Acceleration may occur initially but ceases in the long term.

Abstract

The cosmological effects of the tachyon rolling down to its ground state are discussed by coupling a simple effective field theory for the tachyon field to Einstein gravity. As the tachyon rolls down to the minimum of its potential the universe expands. Depending upon initial conditions, the scale factor may or may not start off accelerating, but ultimately it ceases to do so and the final flat spacetime is either static in the rest frame of the tachyon (if $k=0$) or (if $k=-1$) given by the Milne model.