Penguin-mediated B_(d,s)->VV decays and the Bs - anti-Bs mixing angle

Abstract

In this letter, we propose three different strategies to extract the weak mixing angle phi_s of the Bs system using penguin-mediated decays into vectors, mainly Bs->K*K*, Bs->phi K* and Bs->phi phi. We also provide predictions for the longitudinal branching ratio and CP-asymmetries of Bs->K*K* using a method that combines QCD factorisation with flavour symmetries to relate this decay to its Bd counterpart.