Measurement of the branching fractions of B¯ → D(*)K−KS∗0 and B¯ → D(*)Ds− decays at Belle II

We present measurements of the branching fractions of eight B¯⁰ → D^(*)+K⁻KS^∗0, B⁻ → D^(*)0K⁻KS^∗0 decay channels. The results are based on data from SuperKEKB electron-positron collisions at the Υ(4S) resonance collected with the Belle II detector, corresponding to an integrated luminosity of 362 fb⁻¹. The event yields are extracted from fits to the distributions of the difference between expected and observed B meson energy, and are efficiency-corrected as a function of m(K⁻KS^∗0) and m(D^(*)KS^∗0) in order to avoid dependence on the decay model. These results include the first observation of B¯⁰ → D⁺K⁻KS⁰, B⁻ → D*⁰K⁻KS⁰, and B¯⁰ → D*⁺K⁻KS⁰ decays and a significant improvement in the precision of the other channels compared to previous measurements. The helicity-angle distributions and the invariant mass distributions of the K⁻KS^∗0 systems are compatible with quasi-two-body decays via a resonant transition with spin-parity J^P = 1⁻ for the K⁻KS⁰ systems and J^P = 1⁺ for the K⁻K*⁰ systems. We also present measurements of the branching fractions of four B¯⁰ → D^(*)+Ds⁻, B⁻ → D^(*)0Ds⁻ decay channels with a precision compatible to the current world averages.

Duke Scholars

Author Anselm G. Vossen Physics