Like-sign dimuon charge asymmetry in the decay of B B-bar pairs

We discuss the CP-violating dimuon charge asymmetry of events p p-bar ---> B B-bar X ---> mu mu X in the Standard Model. Our conclusion is that the asymmetry is larger than previously expected and may reach a few percent for the (B_d^0, B-bar_d^0) system. The analysis is also extended to the Two Higgs Doublet Model (Model II).