Measurements of the branching fractions of ${\Xi }_c^0\to {\Xi }^0{\pi }^0$, ${\Xi }_c^0\to {\Xi }^0\eta$, and ${\Xi }_c^0\to {\Xi }^0{\eta }^{\prime }$ and asymmetry parameter of ${\Xi }_c^0\to {\Xi }^0{\pi }^0$

Abstract

We present a study of ${\Xi }_c^0\to {\Xi }^0{\pi }^0$, ${\Xi }_c^0\to {\Xi }^0\eta$, and ${\Xi }_c^0\to {\Xi }^0{\eta }^{\prime }$ decays using the Belle and Belle~II data samples, which have integrated luminosities of 980~${\mathrm{fb}}^{-1}$ and 426~${\mathrm{fb}}^{-1}$, respectively. We measure the following relative branching fractions $$\mathcal{B}({\Xi }_c^0\to {\Xi }^0{\pi }^0)/\mathcal{B}({\Xi }_c^0\to {\Xi }^{-}{\pi }^{+})=0.48\pm 0.02(\mathrm{stat})\pm 0.03(\mathrm{syst}),$$ $$\mathcal{B}({\Xi }_c^0\to {\Xi }^0\eta )/\mathcal{B}({\Xi }_c^0\to {\Xi }^{-}{\pi }^{+})=0.11\pm 0.01(\mathrm{stat})\pm 0.01(\mathrm{syst}),$$ $$\mathcal{B}({\Xi }_c^0\to {\Xi }^0{\eta }^{\prime })/\mathcal{B}({\Xi }_c^0\to {\Xi }^{-}{\pi }^{+})=0.08\pm 0.02(\mathrm{stat})\pm 0.01(\mathrm{syst})$$ for the first time, where the uncertainties are statistical ($\mathrm{stat}$) and systematic ($\mathrm{syst}$). By multiplying by the branching fraction of the normalization mode, $\mathcal{B}({\Xi }_c^0\to {\Xi }^{-}{\pi }^{+})$, we obtain the following absolute branching fraction results $(6.9\pm 0.3(\mathrm{stat})\pm 0.5(\mathrm{syst})\pm 1.3(\mathrm{norm}))\times 10^{-3}$, $(1.6\pm 0.2(\mathrm{stat})\pm 0.2(\mathrm{syst})\pm 0.3(\mathrm{norm}))\times 10^{-3}$, and $(1.2\pm 0.3(\mathrm{stat})\pm 0.1(\mathrm{syst})\pm 0.2(\mathrm{norm}))\times 10^{-3}$, for ${\Xi }_c^0$ decays to ${\Xi }^0{\pi }^0$, ${\Xi }^0\eta$, and ${\Xi }^0{\eta }^{\prime }$ final states, respectively. The third errors are from the uncertainty on $\mathcal{B}({\Xi }_c^0\to {\Xi }^{-}{\pi }^{+})$. The asymmetry parameter for ${\Xi }_c^0\to {\Xi }^0{\pi }^0$ is measured to be $\alpha ({\Xi }_c^0\to {\Xi }^0{\pi }^0)=-0.90\pm 0.15(\mathrm{stat})\pm 0.23(\mathrm{syst})$.

Comments: 23 pages, 5 figures, accepted for publication by JHEP