Physics beyond the standard model has its ups and downs. Ups like mountains in the Netherlands, and downs like the Marianas Trench. Whenever something exciting seems to happen it's the telltale sign that a really big hammer is about to come down.
Last week the D0 experiment at the Tevatron presented the new measurement of the same-sign dimuon charge asymmetry in B-meson decays. This asymmetry probes CP violation in B-mesons, including the $B_s$ mesons that have been less precisely studied than their $B_d$ friends and may still hold surprises in store. D0 claimed that their measurement is inconsistent with the standard model at the 3.2 sigma level and hints to a new physics contribution to the $B_s \bar B_s$ mixing. 3 sigma anomalies in flavor physics are not unheard of, but in this case there were reasons to get excited. One was that the $B_s$ system is a natural place for new physics to show up, because the standard model contribution to the CP-violating mixing phase is tiny, and theoretical predictions are fairly clean. The other reason was that the D0 anomaly seemed to go along well with earlier measurements of CP violation in the $B_s$ system. Namely, the measurement of the $B_s$ decay to $J/\psi \phi$ displayed a 2.1 sigma discrepancy with the standard model, and some claimed the discrepancy is even higher when combined with all other flavor data. In other words, all measurements (except for $B_s \to D_s \mu X$ that however has a larger error) of the phase in the $B_s \bar B_s$ mixing consistently pointed toward new physics.
Not any more. Two days ago D0's rival experiment CDF presented crucial new results at the FPCP conference - a major sabbath of the flavor community. CDF repeated the measurement of the CP violation $B_s \to J/\psi \phi$ on a larger data sample of 5.2 inverse femtobarn, that is with 2 times larger statistics than in the previous measurement. And they see nothing: the result is 0.8 sigma consistent with the standard model.
So at this moment only one experiment claims to see an anomaly in the $B_s$ system, while another measurement of the $B_s \bar B_s$ mixing phase is perfectly consistent with the evil, corrupted standard model. The most likely hypothesis is that D0's result is a fluke and/or systematical uncertainties have been underestimated. Of course, further measurements of the mixing phase may bring another twist to the story...well i dont sound convincing, do I ;-)