First measurement of $\psi (3686)\to \bar{p}{K}^{+}{\Sigma }^{\ast }(1385{)}^0+c.c.$ and $\psi (3686)\to \bar{p}{K}^{\ast }(892{)}^0{\Sigma }^{+}+c.c.$

Abstract

Based on a sample of $(2712.4\pm 14.3)\times 10^6$ $\psi (3686)$ events collected with the BESIII detector at the BEPCII collider, we report the first observation of the decays $\psi (3686)\to \bar{p}{K}^{+}{\Sigma }^{\ast }(1385{)}^0+c.c.$ and $\psi (3686)\to \bar{p}{K}^{\ast }(892{)}^0{\Sigma }^{+}+c.c.$. The corresponding branching fractions are determined to be $\mathcal{B}(\psi (3686)\to \bar{p}{K}^{+}{\Sigma }^{\ast }(1385{)}^0+c.c.)=(3.94\pm 0.15_{\text{stat.}}\pm 0.24_{\text{syst.}})\times 10^{-5}$ and $\mathcal{B}(\psi (3686)\to \bar{p}{K}^{\ast }(892{)}^0{\Sigma }^{+}+c.c.)=(4.93\pm 0.14_{\text{stat.}}\pm 0.30_{\text{syst.}})\times 10^{-5}$. Furthermore, we search for the hidden-strange pentaquark candidates $N_x(1875)$ and $N_x(2100)$ in the invariant mass spectra of $K^{+}{\Sigma }^{\ast }(1385{)}^0$ and $K^{\ast }(892{)}^0{\Sigma }^{+}$, respectively. No significant signals are observed and the upper limits on the branching fractions at the 90% confidence level are $\mathcal{B}(\psi (3686)\to \bar{p}{N}_x(1875)\to \bar{p}{K}^{+}{\Sigma }^{\ast }(1385{)}^0)<1.58\times 10^{-6}$ and $\mathcal{B}(\psi (3686)\to \bar{p}{N}_x(2100)\to \bar{p}{K}^{\ast }(892{)}^0{\Sigma }^{+})<3.09\times 10^{-7}$.