Measuring new-physics parameters in B penguin decays

Abstract

We examine new-physics (NP) effects in B decays with large b¯→s¯ penguin amplitudes. Decays involving b¯→d¯ penguins are assumed to be unaffected. We consider a model-independent parametrization of such NP. We argue that NP strong phases are negligible relative to those of the standard model. This allows us to describe the NP effects in terms of a small number of effective amplitudes ANPq(q=u,d,s,c) and corresponding weak phases Φq. We then consider pairs of neutral B decays which are related by flavour SU(3) in the standard model. One receives a large b¯→s¯ penguin component and has a NP contribution; the other has a b¯→d¯ penguin amplitude and is unaffected by NP. The time-dependent measurement of these two decays allows the measurement of the NP parameters ANPq and Φq. The knowledge of these parameters allows us to rule out many NP models and thus partially identify the new physics.