Mixing asymmetries in B meson systems, the D0 like-sign dimuon asymmetry, and generic new physics

Abstract

The measurement of a large like-sign dimuon asymmetry ASLb 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 ΔB≠0 transitions. In this work we analyze how the natural suppression of ASLb 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 3×3 unitary Cabibbo-Kobayashi-Maskawa matrix, and show how, within this framework, a significant enhancement over Standard Model expectations for ASLb is easily reachable through enhancements of the semileptonic asymmetries ASLd and ASLs of both Bd0-B¯d0 and Bs0-B¯s0 systems. Despite being insufficient to reproduce the D0 measurement, such deviations from SM expectations may be probed by the LHCb experiment.