Measurement of the branching fraction for $B^{0} \to \pi^{0} \pi^{0}$ decays reconstructed in 2019–2020 Belle II data

Sumitted to PubDB: 2021-07-06

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Authors	Francis Pham, Martin Sevior
Date	July 6, 2021
Belle II Number	BELLE2-CONF-PH-2021-003
Abstract	We report the first reconstruction of the $B^{0} \to \pi^{0} \pi^{0}$ decay mode at Belle II using samples of 2019 and 2020 data that correspond to 62.8 \invfb of integrated luminosity. We find $14.0^{+6.8}_{-5.6}$ signal decays, corresponding to a significance of 3.4 standard deviations and determine a branching ratio of $\mathcal{B}(\Bpipi) = [0.98^{+0.48}_{-0.39} \pm 0.27] \times 10^{-6}$. The results agree with previous determinations and contribute important information to an early assessment of detector performance and Belle II's potential for future determinations of $\alpha/\phi_2$ using $\PB \to \pi \pi$ modes.