210 research outputs found
Implications of Two-component Dark Matter Induced by Forbidden Channels and Thermal Freeze-out
We consider a model of two-component dark matter based on a hidden
symmetry, in which relic densities of the dark matter are determined by
forbidden channels and thermal freeze-out. The hidden symmetry is
spontaneously broken to a residual symmetry, and the lightest
charged particle can be a dark matter candidate. Moreover,
depending on the mass hierarchy in the dark sector, we have two-component dark
matter. We show that the relic density of the lighter dark matter component can
be determined by forbidden annihilation channels which require larger couplings
compared to the normal freeze-out mechanism. As a result, a large
self-interaction of the lighter dark matter component can be induced, which may
solve small scale problems of CDM model. On the other hand, the
heavier dark matter component is produced by normal freeze-out mechanism. We
find that interesting implications emerge between the two dark matter
components in this framework. We explore detectabilities of these dark matter
particles and show some parameter space can be tested by the SHiP experiment.Comment: 23 pages, 9 figures, 1 table, version to appear in JCA
Physics potential of future long baseline neutrino oscillation experiments with KEK-JAERI HIPA
We study physics potential of Very Long Base-Line (VLBL) Neutrino-Oscillation
Experiments with the High Intensity Proton Accelerator, which will be completed
by the year 2007 in Tokai-village, Japan. As a target, a 100 kton-level
water-erenkov detector is considered at 2,100 km away. Assuming
the pulsed narrow-band beams, we study sensitivity of such
experiments to the neutrino mass hierarchy, the mass-squared differences, one
CP phase and three angles of the lepton-flavor-mixing matrix. We find that
experiments at a distance 2,100 km can determine the neutrino mass hierarchy if
the mixing matrix element is not too small. The CP phase and
can be constrained if the large-mixing-angle solution of the
solar-neutrino deficit is realized.Comment: 6 pages, LaTeX, Talk given at 5th KEK Topical Conference (KEKTC5),
KEK, Tsukuba, Japan, November 200
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