The Baryogenesis Window in the MSSM

Abstract

Electroweak baryogenesis provides an attractive explanation of the origin of the matter-antimatter 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_{\tilde t}) 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_{\tilde t},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\lesssim 127 GeV and m_{\tilde t}\lesssim 120 GeV, implying that this scenario will be probed at the LHC.

Comments: 26 pages, 6 figures; comments added