The D0 same-charge dimuon asymmetry and possibile new CP violation sources in the $B_s-{\bar{B}}_s$ system

Abstract

Recently, the D0 collaboration reported a large CP violation in the same-sign dimuon charge asymmetry which has the $3.2\sigma$ deviation from the value estimated in the Standard Model. In this paper, several new physics models are considered: the MSSM, two Higgs doublet model, the recent dodeca model, and a new $Z^{\prime }$ model. Generally, it is hard to achieve such a large CP violation consistently with other experimental constraints. We find that a scheme with extra non-anomalous U(1)${}^{\prime }$ gauge symmetry is barely consistent. In general, the extra $Z^{\prime }$ gauge boson induces the flavor changing neutral current interactions at tree level, which is the basic reason allowing a large new physics CP violation. To preserve the U(1)${}^{\prime }$ 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.

Comments: 12 pages, 13 figures