The baryogenesis window in the MSSM

Electroweak baryogenesis provides an attractive explanation of the origin of the matter-anti matter asymmetry that relies on physics at the weak scale and thus it is testable at present and near future high-energy physics experiments. Although this scenario may not be realized within the Standard Model, it can be accommodated within the MSSM provided there are new CP-violating phases and the lightest stop mass is smaller than the top-quark mass. In this work we provide an evaluation of the values of the stop (m(i)) and Higgs (m(H)) masses consistent with the requirements of electroweak baryogenesis based on an analysis that makes use of the renormalization group improved Higgs and stop potentials, and including the dominant two-loop effects at high temperature. We find an allowed window in the (m(i), m(H))-plane, consistent with all present experimental data, where there is a strongly first-order electroweak phase transition and where the electroweak vacuum is metastable but sufficiently long-lived. In particular we obtain absolute upper bounds on the Higgs and stop masses, m(H) less than or similar to 127 GeV and m(i) less than or similar to 120 GeV, implying that this scenario will be probed at the LHC. (C) 2008 Elsevier B.V. All rights reserved.