Measurement of the branching fractions of B ¯ $$ \overline{B} $$ → D (*) K − K S ∗ 0 $$ {K}_{(S)}^{\left(\ast \right)0} $$ and B ¯ $$ \overline{B} $$ → D (*) D s − $$ {D}_s^{-} $$ decays at Belle II

Abstract

Abstract We present measurements of the branching fractions of eight B ¯ 0 $$ {\overline{B}}^0 $$ → D (*)+ K − K S ∗ 0 $$ {K}_{(S)}^{\left(\ast \right)0} $$ , B − → D (*)0 K − K S ∗ 0 $$ {K}_{(S)}^{\left(\ast \right)0} $$ 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 − K S ∗ 0 $$ {K}_{(S)}^{\left(\ast \right)0} $$ ) and m(D (*) K S ∗ 0 $$ {K}_{(S)}^{\left(\ast \right)0} $$ ) in order to avoid dependence on the decay model. These results include the first observation of B ¯ 0 $$ {\overline{B}}^0 $$ → D + K − K S 0 $$ {K}_S^0 $$ , B − → D* 0 K − K S 0 $$ {K}_S^0 $$ , and B ¯ 0 $$ {\overline{B}}^0 $$ → D* + K − K S 0 $$ {K}_S^0 $$ 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 S ∗ 0 $$ {K}_{(S)}^{\left(\ast \right)0} $$ systems are compatible with quasi-two-body decays via a resonant transition with spin-parity J P = 1− for the K − K S 0 $$ {K}_S^0 $$ systems and J P = 1+ for the K − K* 0 systems. We also present measurements of the branching fractions of four B ¯ 0 $$ {\overline{B}}^0 $$ → D (*)+ D s − $$ {D}_s^{-} $$ , B − → D (*)0 D s − $$ {D}_s^{-} $$ decay channels with a precision compatible to the current world averages.

Keywords

• B Physics
• Branching fraction
• e +-e − Experiments
• Particle and Resonance Production