D0 same-charge dimuon asymmetry and possible new CP violation sources in the Bs-Bs system

Recently, the D0 Collaboration reported a large CP violation in the same-sign dimuon charge asymmetry which has the 3.2σ deviation from the value estimated in the standard model. In this paper, several new physics models are considered: the minimal supersymmetric standard model, the two Higgs doublet model, the recent dodeca model, and a new Z' model. Generally, it is hard to achieve such a large CP violation consistently with other experimental constraints. We find that a scheme with extra nonanomalous U(1)' gauge symmetry is barely consistent. In general, the extra Z' gauge boson induces the flavor changing neutral current interactions at tree level, which is the basic reason for allowing a large new physics CP violation. To preserve the U(1)' symmetry at high energy, SU(2)L singlet exotic heavy quarks of mass above 1 TeV and the standard model gauge singlet scalars are introduced.