  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.
