Search for a pentaquark state decaying into $pJ/\ddot{I}ˆ$ in $\hat{I}\yen (1,2S)$ inclusive decays at Belle

Abstract

Using the data samples of 102 million $\hat{I}\yen (1S)$ and 158 million $\hat{I}\yen (2S)$ events collected by the Belle detector, we search for a pentaquark state in the $pJ/\ddot{I}ˆ$ final state from $\hat{I}\yen (1,2S)$ inclusive decays. Here, the charge-conjugate $\bar{p}J/\ddot{I}ˆ$ is included. We observe clear $pJ/\ddot{I}ˆ$ production in $\hat{I}\yen (1,2S)$ decays and measure the branching fractions to be $B[\hat{I}\yen (1S)\to pJ/\ddot{I}ˆ+anything]=[8.1\pm 0.6(stat.)\pm 0.5(syst.)]\times 10^{-5}$ and $B[\hat{I}\yen (2S)\to pJ/\ddot{I}ˆ+anything]=[4.3\pm 0.5(stat.)\pm 0.4(syst.)]\times 10^{-5}$. We also measure the cross section of inclusive $pJ/\ddot{I}ˆ$ production in $e^{+}{e}^{-}$ annihilation to be $\ddot{I}ƒ(e^{+}{e}^{-}\to pJ/\ddot{I}ˆ+anything)=[108\pm 11(stat.)\pm 6(syst.)]$~fb at $\sqrt{s}=10.52GeV$ using an 89.5~fb${}^{-1}$ continuum data sample. There is no significant $P_c(4312{)}^{+}$, $P_c(4440{)}^{+}$ or $P_c(4457{)}^{+}$ signal found in the $pJ/\ddot{I}ˆ$ final states in $\hat{I}\yen (1,2S)$ inclusive decays. We determine the upper limits of $B[\hat{I}\yen (1,2S)\to P_c^{+}+anything]\cdot B(P_c^{+}\to pJ/\ddot{I}ˆ)$ to be at the $10^{-6}$ level.