Abstract
In certain implementations of the brane inflationary paradigm, the exit from inflationoccurs when the branes annihilate through tachyon condensation. We investigate variouscosmological effects produced by this tachyonic era. We find that only a very small regionof the parameter space (corresponding to slow roll with tiny inflaton mass) allows for thetachyon to contribute some e-folds to inflation. In addition, non-adiabatic densityperturbations are generated at the end of inflation. When the brane is movingrelativistically this contribution can be of the same order as fluctuations produced 55e-folds before the end of inflation. The additional contribution is exactly scale invariant andenhances the tensor/scalar ratio. Additional non-Gaussianities will also be generated,sharpening current constraints on Dirac–Born–Infeld-type models which already predict asignificantly non-Gaussian signal.
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