Looking from the East at an Elephant Trotting West : Direct CP Violation in B Decays

With the time dependant CP asymmetry in Bd(t) → ψKS well measured, the most powerful method to search for direct CP violation in Bd decays is to analyze whether the CP asymmetry of other transitions like Bd(t) → π π, ηKS etc. can be described by a sin term taken from Bd(t) → ψKS and without a cos term. The failure of such a constrained fit would establish direct CP violation (even if no CP asymmetry were observed in these other modes). Prologos The occurrance of large CP violation in Bd → ψKS predicted in 1981 [1] has been established in 2001 [2, 3]. BABAR and BELLE have just now presented updates: sin(2φ1) = 0.82± 0.12± 0.05 BELLE [5] (1) sin(2β) = 0.75± 0.09± 0.04 BABAR [4] (2) These findings are of a paradigmatic nature in several respects even beyond the obvious one that they constitute the first observation of CP violation outside the KL system: (i) The effect being truly large ‘de-mystifies’ CP violation: for it tells us that if CP invariance can be broken, that violation is not intrinsically small [6]. (ii) While the observed asymmetry could still contain sizeable contributions from New Physics, it conforms to the CKM prediction in a completely unforced way. It With due apologies to Sir Charles Laughton.