Supersymmetric dark matter as a clock
Monday 23 February, 2:30 pm, Curia II
Piero Ullio (SISSA, Italy)
rse AT caltech.astro.edu

It is a remarkable coincidence that the thermal relic abundance of
neutralinos in supersymmetric extensions to the standard model
is roughly of the order needed to account for dark matter in the
Universe. As in any process involving departure from thermal
equilibrium, the freeze out of neutralinos, at a temperature of
a few GeVs, can be understood in terms of a particle interaction rate
falling below the expansion rate of the Universe. When considering
these two competing effects, the focus is usually on the former,
with the expansion rate fixed according to an extrapolation in
a radiation dominated Universe. On the other hand, supersymmetric
dark matter can be regarded a viable tool to test eventual departures
from this picture, induced, e.g., by a quintessence field playing
a role in the early history of the Universe.