Implications of the dimuon CP asymmetry in B_{d,s} decays

Understand

The D0 Collaboration reported a 3.2sigma deviation from the standard model prediction in the like-sign dimuon asymmetry.

• Assuming that new physics contributes only to B_{d,s} mixing, we show that the data can be analyzed without using the theoretical calculation of \Delta\Gamma_s, allowing for robust interpretations.
• We find that this framework gives a good fit to all measurements, including the recent CDF S_{\psi\phi} result.
• The data allow universal new physics with similar contributions relative to the SM in the B_d and B_s systems, but favors a larger deviation in B_s than in B_d mixing.