Measurement of the branching fraction and $\it CP$-violating asymmetry of the decay $B^{0} \rightarrow \pi^{0} \pi^{0}$ using $387$ million bottom-antibottom meson pairs in Belle II data

TL;DR

This study measures the decay rate and CP asymmetry of B0 to pi0 pi0 decays using Belle II data, providing insights into CP violation and decay processes in the B meson system.

Contribution

First measurement of the branching fraction and CP asymmetry for B0 to pi0 pi0 decays using Belle II data with 387 million B meson pairs.

Findings

Branching fraction: (1.25 ± 0.23)×10^{-6}

CP asymmetry: 0.03 ± 0.30

126 ± 20 signal decays identified

Abstract

We measure the branching fraction and $\it CP$-violating flavor-dependent rate asymmetry of $B^{0} \to \pi^{0} \pi^{0}$ decays reconstructed using the Belle II detector in an electron-positron collision sample containing $387 \times 10^{6}$ $B\overline{B}$ pairs. Using an optimized event selection, we find $126\pm 20$ signal decays in a fit to background-discriminating and flavor-sensitive distributions. The resulting branching fraction is $(1.25 \pm 0.23)\times 10^{-6}$ and the $\it CP$-violating asymmetry is $0.03 \pm 0.30$.