Branching fractions, polarisation and asymmetries of B→VVB→VV decays

We calculate the hard-scattering kernels relevant to the negative-helicity decay amplitude in B   decays to two vector mesons in the framework of QCD factorisation. We then perform a comprehensive analysis of the 34 B→VVB→VV decays, including BsBs decays and the complete set of polarisation observables. We find considerable uncertainties from weak annihilation and the non-factorisation of spectator-scattering. Large longitudinal polarisation is expected with certainty only for a few tree-dominated colour-allowed modes, which receive small penguin and spectator-scattering contributions. This allows for an accurate determination of the CKM angle α (or γ  ) from SLρρ resulting in α=(85.6−7.3+7.4)°. We also emphasize that the ρK∗ρK∗ system is ideal for an investigation of electroweak penguin effects.