Measurements of the branching fractions of Ξc0→Ξ0π0, Ξc0→Ξ0η, and Ξc0→Ξ0η′ and asymmetry parameter of Ξc0→Ξ0π0

Abstract

We present a study of ${\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^0{\pi }^0$, ${\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^0\eta$, and ${\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^0{\eta }^{\prime }$ decays using the Belle and Belle II data samples, which have integrated luminosities of 980 fb⁻¹ and 426 fb⁻¹, respectively. We measure the following relative branching fractions$$\begin{array}{c}\mathcal{B}\left({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^0{\pi }^0\right)/\mathcal{B}\left({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^{-}{\pi }^{+}\right)=0.48\pm 0.02\left(\text{stat}\right)\pm 0.03\left(\text{syst}\right),\\ \mathcal{B}\left({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^0\eta \right)/\mathcal{B}\left({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^{-}{\pi }^{+}\right)=0.11\pm 0.01\left(\text{stat}\right)\pm 0.01\left(\text{syst}\right),\\ \mathcal{B}\left({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^0{\eta }^{\prime }\right)/\mathcal{B}\left({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^{-}{\pi }^{+}\right)=0.08\pm 0.02\left(\text{stat}\right)\pm 0.01\left(\text{syst}\right)\end{array}$$

for the first time, where the uncertainties are statistical (stat) and systematic (syst). By multiplying by the branching fraction of the normalization mode, $\mathcal{B}\left({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^{-}{\pi }^{+}\right)$, we obtain the following absolute branching fraction results$$\begin{array}{c}\mathcal{B}\left({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^0{\pi }^0\right)=\left(6.9\pm 0.3\left(\text{stat}\right)\pm 0.5\left(\text{syst}\right)\pm 1.3\left(norm\right)\right)\times {10}^{-3},\\ \mathcal{B}\left({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^0\eta \right)=\left(1.6\pm 0.2\left(\text{stat}\right)\pm 0.2\left(\text{syst}\right)\pm 0.3\left(norm\right)\right)\times {10}^{-3},\\ \mathcal{B}\left({\Xi }_c^0\to {\mathrm{\Xi }}^0{\eta }^{\prime }\right)=\left(1.2\pm 0.3\left(\text{stat}\right)\pm 0.1\left(\text{syst}\right)\pm 0.2\left(norm\right)\right)\times {10}^{-3},\end{array}$$

where the third uncertainties are from $\mathcal{B}\left({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^{-}{\pi }^{+}\right)$. The asymmetry parameter for ${\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^0{\pi }^0$ is measured to be $\alpha \left({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^0{\pi }^0\right)=-0.90\pm 0.15\left(\text{stat}\right)\pm 0.23\left(\text{syst}\right)$.