JHEP 2024, (2024)

ISSN: 1029-8479, SCIE

Measurement of the branching fractions of B → D(∗)K−K (∗)0 (S) and B → D(∗)D− s decays at Belle II

Belle II Collaboration (I. Adachi, ..., N. Anh Ky, ...)

We present measurements of the branching fractions of eight B0 → D(∗)+K−K (∗)0 (S) , B− → D(∗)0K−K (∗)0 (S) 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−K (∗)0 (S) ) and m(D(∗)K (∗)0 (S) ) in order to avoid dependence on the decay model. These results include the first observation of B0 → D+K−K0 S , B− → D∗0K−K0 S , and B0 → D∗+K−K0 S 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−K (∗)0 (S) systems are compatible with quasi-two-body decays via a resonant transition with spin-parity J P = 1− for the K−K0 S systems and J P = 1+ for the K−K∗0 systems. We also present measurements of the branching fractions of four B0 → D(∗)+D− s , B− → D(∗)0D− s decay channels with a precision compatible to the current world averages.

DOI: https://doi.org/10.48550/arXiv.2406.06277

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