A precise isospin analysis of B -> Dbar(*) D(*) K decays

We present a precise isospin analysis of the B -> Dbar(*) D(*) K decays using new recent experimental measurements on these final states. The decays B -> Dbar(*) D(*) K, originating from b -> c cbar s transitions, are linked by a rich set of isospin properties. The isospin relations that connect the decay modes are presented and a fit is performed to obtain the isospin amplitudes and phases. We discuss the results of the fit and present a new measurement of the ratio of branching fractions BR(Upsilon(4S) -> B+ B-) and BR(Upsilon(4S) -> B0 B0bar). We finally discuss the implications of our findings for the measurement of the unitarity matrix parameters sin(2 beta) and cos(2 beta) using these decays.