Light W - ino dark matter in brane world cosmology Takeshi

Osamu Seto Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QJ, United Kingdom Abstract The thermal relic density of the W-ino-like neutralino dark matter in brane world cosmology is studied. The expansion law at a high energy regime in brane world cosmology is modified from the one in standard cosmology, and the resultant relic density can be enhanced if the fivedimensional Planck mass M5 is low enough. We calculate the W-ino-like neutralino relic density in the anomaly mediated supersymmetry breaking scenario and show that the allowed region is dramatically modified from the one in standard cosmology and the W-ino-like neutralino with mass of order 100 GeV can be a good candidate for dark matter. Since the allowed region disappears eventually asM5 decreases, we can find a lower bound onM5 & 100 TeV according to the neutralino dark matter hypothesis, namely the lower bound in order for the allowed region of neutralino dark matter to exist.