Diagnostic for new physics in B _ú 7__K decays

摘要

A recent analysis of B_úK__ decays concludes that present data do not clearly indicate whether (i) the standard model (or _¤l = 0 new physics) is sufficient, or (ii)_¤l = 1 new physics is needed. We show that these two possibilities can be distinguished by whether a sum rule relating the CP asymmetriesof the four B_úK__ decays is valid. If case (i) is favored, the sum rule holds, and one predicts Acp(__~0k~0) = -0.15, while in case (ii) fits to new physics involving large values of a color-suppressed tree amplitude entail A_cp(__~0k~0)=-0.03. The current experimental average Acp(jr°K°) = _0.01 ± 0.10 must be measured a factor of at least three times more precisely in order to distinguish between the two cases.