XXth International Conference on Neutrino Physics and Astrophysics
E.Torrente
Relic Neutralino Density in Scenarios with Intermediate
Unification Scale
We analyse the relic neutralino density in supersymmetric models with
an intermediate unification scale. In particular, we present concrete
cosmological scenarios where the reheating temperature is as small as
O(1-1000 MeV). When this temperature is associated to the decay of
moduli fields producing neutralinos, we show that the relic abundance
increases considerably with respect to the standard thermal
production. Thus the neutralino becomes a good dark matter candidate
with 0.1 <~ Omega h^2 <~ 0.3, even for regions of the parameter space
where large neutralino-nucleon cross sections, compatible with current
dark matter experiments, are present. This is obtained for
intermediate scales M_I ~ 10^11 - 10^14 GeV, and moduli masses m_phi ~
100 - 1000 GeV. On the other hand, when the above temperature is
associated to the decay of an inflaton field, the relic abundance is
too small.