Measuring the CP Angle \beta in Hadronic b\to s Penguin Decays

Abstract

Asymmetric e^+e^- colliders running on the \Upsilon(4S) (B factories) will much more readily measure CP-violating asymmetries in the decays of B_d^0 and B^\pm mesons than in the decays of B_s^0 mesons. As such, they will seemingly not be able to probe new phases in Bs-Bs(bar) mixing, i.e. in b\to s transitions. However, by measuring the CP angle \beta via b \to s hadronic penguin decays such as B_d^0 \to \eta'\ks and B_d^0 \to\phi\ks, and comparing its value to that obtained in B_d^0 \to\Psi\ks, it is possible to detect the presence of new physics in the b\to s flavour-changing neutral current. Recent CLEO results are encouraging in this regard. They suggest that the branching ratio of the b\to s penguin decay B_d^0 \to \eta'\ks is anomalously large, about 4 \times 10^{-5}, which will make it much easier to search for new physics in b\to s transitions.