Determining weak phases from B → J/ψP decays

The decay B -> J/psi K-S remains the most important source of information for the B-d mixing phase, determined by the Cabibbo, Kobayashi, and Maskawa (CKM) angle beta in the standard model. When aiming at a precision appropriate for present and coming high luminosity colliders, the corresponding hadronic matrix elements are a major obstacle, as their precise calculation is still not feasible with existing methods. Flavor symmetries offer a possibility to extract them from data, however, again with limited precision. In this article, we propose a framework to take subleading contributions in B-u,B-d,B-s -> J/psi P decays into account, P is an element of {pi, K, (eta(8))}, using an SU(3) analysis, together with the leading corrections to the symmetry limit. This allows for a model-independent extraction of the Bd mixing phase adequate for coming high precision data, and additionally yields information on possible new physics contributions in these modes. We find the penguin-induced correction to be small, Delta S-J/psi KS less than or similar to 0.01, a limit that can be improved with coming data on CP asymmetries and branching ratios. Finally, the sensitivity on the CKM angle gamma from these modes is critically examined, yielding a less optimistic picture than previously envisaged.