Measurements of branching fractions and direct CP asymmetries in $B^0\to K^{+}{\pi }^{-}$, $B^{+}\to K_{\mathrm{S}}^0{\pi }^{+}$ and $B^0\to {\pi }^{+}{\pi }^{-}$ using 2019 and 2020 data

Abstract

We report updated measurements of branching fractions ($\mathcal{B}$) and CP-violating charge asymmetries (${\mathcal{A}}_{\mathrm{CP}}$) for charmless $B$ decays at Belle II, which operates on or near the ${\rm Y}$(4S) resonance at the SuperKEKB asymmetric energy $e^{+}{e}^{-}$ collider. We use samples of 2019 and 2020 data corresponding to 62.8 fb${}^{-1}$ of integrated luminosity. The samples are analysed using two-dimensional fits in $\Delta E$ and $M_{bc}$ to determine signal yields of approximately 568, 103, and 115 decays for the channels $B^0\to K^{+}{\pi }^{-}$, $B^{+}\to K_{\mathrm{S}}^0{\pi }^{+}$, and $B^0\to {\pi }^{+}{\pi }^{-}$, respectively. Signal yields are corrected for efficiencies determined from simulation and control data samples to obtain branching fractions and CP-violating asymmetries for flavour-specific channels. The results are compatible with known determinations and contribute important information to an early assessment of Belle II detector performance.

arXiv comment23 pages, 8 figures. Supporting material for Spring 2021 conferences

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Cited by in corpus (1)

• Complete analysis of all $B\to \pi K$ decays