A precise isospin analysis of B→D¯(⁎)D(⁎)K decays

We present a precise isospin analysis of the B→D¯(⁎)D(⁎)K decays using new recent experimental measurements on these final states. The decays B→D¯(⁎)D(⁎)K, originating from b→cc¯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 B(ϒ(4S)→B+B−) and B(ϒ(4S)→B0B¯0). We finally discuss the implications of our findings for the measurement of the unitarity matrix parameters sin(2β) and cos(2β) using these decays.