Measurement of the branching fraction of the $B^0\to K_S^0{\pi }^0\gamma$ decay using 190 fb${}^{-1}$ of Belle II data

Abstract

We report the measurement of the branching fraction of the $B^0\to K_S^0{\pi }^0\gamma$ decay in $e^{+}{e}^{-}\to {\rm Y}(4S)\to B\overline{B}$ data recorded by the Belle II experiment at the SuperKEKB asymmetric-energy collider and corresponding to 190 fb${}^{-1}$ of integrated luminosity. The signal yield is measured to be $121\pm 29(stat.)$, leading to the branching fraction $\mathcal{B}\left(B^0\to K_S^0{\pi }^0\gamma \right)=\left(7.3\pm 1.8(stat.)\pm 1.0(syst.)\right)\times 10^{-6}$, which agrees with the known value.

10 pages, 3 figures