An alternative approach to tachyon cosmology
  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.
