204 research outputs found
Non-Baryonic Dark Matter -- A Theoretical Perspective
I review axions, neutralinos, axinos, gravitinos and super-massive Wimpzillas
as dark matter candidates.Comment: Invited review talk at COSMO-98, the Second International Workshop on
Particle Physics and the Early Universe, Asilomar, USA, November 15-20, 199
Non-Baryonic Dark Matter
There exist several well-motivated candidates for non-baryonic cold dark
matter, including neutralinos, axions, axinos, gravitinos, Wimpzillas. I review
the dark matter properties of the neutralino and the current status of its
detection. I also discuss the axino as a new interesting alternative.Comment: Invited plenary review talk given at 6th International Workshop on
Topics in Astroparticle and Underground Physics (TAUP 99), 6-10 September,
1999, Paris, Franc
Axino - New Candidate for Cold Dark Matter
Supersymmetric extensions of the Standard Model when combined with the
Peccei-Quinn solution to the strong CP problem necessarily contain also the
axino, the fermionic partner of the axion. In contrast to the neutralino and
the gravitino, the axino mass is generically not of the order of the
supersymmetry breaking scale and can be much smaller. The axino is therefore an
intriguing candidate for a stable superpartner. The axinos are a natural
candidate for cold dark matter in the Universe when they are generated
non-thermally through out-of-equilibrium neutralino decays or via a competing
thermal production mechanism through scatterings and decays of particles in the
plasma. We identify axino masses in the range of tens of MeV to several GeV
(depending on the scenario) as corresponding to cold axino relics if the
reheating temperature T_R is less than about 5 \times 10^4 GeV. At higher T_R
and lower mass, axinos could constitute warm dark matter. In the scenario with
axinos as stable relics the gravitino problem finds a natural solution. The
lightest superpartner of the Standard Model spectrum will remain stable in
high-energy detectors but may be either neutral or charged. The usual
constraint Omega*h^2<1 on the relic abundance of the lightest neutralino does
not hold.Comment: Based on invited plenary talks at the 4th International Workshop on
Particle Physics and the Early Universe (COSMO-2000), Cheju, Cheju Island,
Korea, September 4-8, 2000 and the 3rd International Workshop on the
Identification of Dark Matter (IDM-2000), York, England, 18-22 September 200
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