The measurement of a large like-sign dimuon asymmetry $A_{\mathrm{SL}}^b$ by the D0 experiment at the Tevatron departs noticeably from Standard Model (SM) expectations and it may be interpreted as a hint of physics beyond the Standard Model contributing to $\mathrm{\Delta }B\ne 0$ transitions. In this work we analyze how the natural suppression of $A_{\mathrm{SL}}^b$ in the SM can be circumvented by new physics. We consider generic Standard Model extensions where the charged current mixing matrix is enlarged with respect to the usual $3\times 3$ unitary Cabibbo-Kobayashi-Maskawa matrix, and show how, within this framework, a significant enhancement over Standard Model expectations for $A_{\mathrm{SL}}^b$ is easily reachable through enhancements of the semileptonic asymmetries $A_{\mathrm{SL}}^d$ and $A_{\mathrm{SL}}^s$ of both $B_d^0\text{−}{\overline{B}}_d^0$ and $B_s^0\text{−}{\overline{B}}_s^0$ systems. Despite being insufficient to reproduce the D0 measurement, such deviations from SM expectations may be probed by the LHCb experiment.

• Received 28 October 2014

DOI:https://doi.org/10.1103/PhysRevD.91.035013