643 research outputs found
Relic density of dark matter in brane world cosmology
We investigate the thermal relic density of the cold dark matter in the
context of the brane world cosmology. Since the expansion law in a high energy
regime is modified from the one in the standard cosmology, if the dark matter
decouples in such a high energy regime its relic number density is affected by
this modified expansion law. We derive analytic formulas for the number density
of the dark matter. It is found that the resultant relic density is
characterized by the ``transition temperature'' at which the modified expansion
law in the brane world cosmology is connecting with the standard one, and can
be considerably enhanced compared to that in the standard cosmology, if the
transition temperature is low enough.Comment: 8 pages, no figure, the version accepted for publication in
Phys.Rev.
Superheavy WIMP dark matter from incomplete thermalization
Although it is usually thought that a class of weakly interacting massive
particle (WIMP) dark matters (DMs), which have the vector coupling with the
boson, is denied by null results of the direct DM searches, such WIMP DMs are
still viable if they are superheavy with the mass of GeV.
In the future, the superheavy WIMP DMs can be searched up to GeV, which corresponds to the so-called neutrino floor limit. We show
that the observed abundance of for a
superheavy WIMP DM can be reproduced by a suitable reheating temperature of
after inflation, if the direct inflaton decay into DM is
negligible or kinematically forbidden.Comment: 11 pages, 2 figure
Neutralino dark matter in brane world cosmology
The thermal relic density of the neutralino dark matter in the brane world
cosmology is studied. Since the expansion law at a high energy regime in the
brane world cosmology is modified from the one in the standard cosmology, the
resultant relic density can be altered. It has been found that, if the five
dimensional Planck mass is lower than TeV, the brane world
cosmological effect is significant at the decoupling time and the resultant
relic density is enhanced. We calculate the neutralino relic density in the
Constrained Minimal Supersymmetric Standard Model (CMSSM) and show that the
allowed region is dramatically modified from the one in the standard cosmology
and eventually disappears as is decreasing. We also find a new lower
bound on TeV based on the neutralino dark matter hypothesis,
namely the lower bound in order for the allowed region of the neutralino dark
matter to exist.Comment: 12 pages, 8 figure
Light wino dark matter in brane world cosmology
The thermal relic density of the wino-like neutralino dark matter in the
brane world cosmology is studied. The expansion law at a high energy regime in
the brane world cosmology is modified from the one in the standard cosmology,
and the resultant relic density can be enhanced if the five dimensional Planck
mass is low enough. We calculate the wino-like neutralino relic density
in the anomaly mediated supersymmetry breaking scenario and show that the
allowed region is dramatically modified from the one in the standard cosmology
and the wino-like neutralino with mass of order 100 GeV can be a good candidate
for the dark matter. Since the allowed region disappears eventually as is
decreasing, we can find a lower bound on TeV according to the
neutralino dark matter hypothesis, namely the lower bound in order for the
allowed region of the neutralino dark matter to exist.Comment: 16 pages, 9 figures, final versio
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