Tachyons in Throat Cosmology

Tachyonic 5d scalars are generically present in Randall-Sundrum-like models. In particular, they are known to be part of the 5d effective description of the Klebanov-Strassler throat. When moving from the IR to the UV region, the 5d bulk profile of Kaluza-Klein excitations of tachyons decays more slowly than that of massless scalars or the graviton. As a result, tachyons in many cases dominate the coupling between IR- and UV-localized sectors, leading to a very significant enhancement of energy-transfer or decay rates from the IR to the UV. This can dramatically affect the reheating of the Standard Model after brane inflation and the decay of throat dark matter.