Light Neutralino Dark Matter in Gaugino Non-Universal Models
We examine the cosmology and the astrophysical signals produced by neutralino dark matter in the frame of an effective MSSM model without gauginomass unification at a grand unification scale. As a consequence of the recent data on precision cosmology, we can set an absolute lower bound of 6 GeV on the neutralino mass. This limit changes to 25 GeV if the pseudoscalar higgs is heavier than 180 GeV. The light neutralinos allowed in this class of supersymmetric models provide quite sizeable direct detection rates. We show how they compare to the direct detection esperimental sensitivites: the predicted rates are largely compatible with the annual-modulation data of the DAMA Collaboration; the comparison with the upper bounds of the CDMS and EDELWEISS Collaborations shows that limits for neutralino masses below 25–30 GeV can be set for a standard isothermal halo. As for the annihilation signals, we find that only low-energy antiprotons and antideuterons are potentially able to set constraints on very low-mass neutralinos, below 20–25 GeV. The gamma-ray signal requires significantly steep profiles or substantial clumpiness in order to reach detectable levels. The up-going muon signal at neutrino telescopes is largely below experimental sensitivities for the neutrino flux coming from the Sun, while for the flux from the Earth an improvement of about one order of magnitude in experimental sensitivities with a low energy threshold can make accessible neutralino masses close to O, Si and Mg masses, for which resonant capture is operative.
KeywordsDark Matter Cold Dark Matter Light Neutralinos Galactic Halo Neutralino Mass
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