Inflation from a tachyon fluid?

Motivated by recent works of Sen [hep-th/0203211, hep-th/0203265] and Gibbons [hep-th/0204008], we study the evolution of a flat and homogeneous universe dominated by tachyon matter. In particular, we analyze the necessary conditions for inflation in the early roll of a single tachyon field. Comparison with string theory reveals that the potential is too steep to explain the fluctuations in the CMBR. We suggest a scenario based on the simultaneous decay of many branes and comment on the issue of reheating of the universe after tachyon rolling. (C) 2002 Elsevier Science B.V. All rights reserved.