Neutralino dark matter and electroweak baryogenesis in the MSSM

We calculate the relic neutralino abundance in the presence of a light top squark, which is required by electroweak baryogenesis, within the minimal supersymmetric standard model. We show that there are three distinct regions of parameter space where the relic density is consistent with the present experimental limits. Tevatron experiments can find the light stop in most of the examined parameter space. In the stop-neutralino co-annihilation region, however, the mass difference between the light stop and the lightest neutralino varies between 15 and 30 GeV, presenting a challenge for stop searches at hadron colliders. We also present the prospects for direct detection of dark matter, which provides a complementary way of testing this scenario. (author)