Search for $\hat{I}\yen (1S,2S)\to Z_c^{+}{Z}_c^{(\prime )-}$ and $e^{+}{e}^{-}\to Z_c^{+}{Z}_c^{(\prime )-}$ at $\sqrt{s}$ = 10.52, 10.58, and 10.867 GeV

Abstract

The first search for $Z_c$ pair production in $\hat{I}\yen (1S)$ and $\hat{I}\yen (2S)$ decays and in $e^{+}{e}^{-}$ annihilation at $\sqrt{s}$ = 10.52, 10.58, and 10.867 GeV is conducted using data collected with the Belle detector at the KEKB asymmetric energy electron-positron collider. No significant signals are observed in any of the studied modes, and the 90\% credibility level upper limits on their product branching fractions in $\hat{I}\yen (1S)$ and $\hat{I}\yen (2S)$ decays ($\mathcal{B}(\hat{I}\yen (1S,2S)\to Z_c^{+}{Z}_c^{(\prime )-})\times \mathcal{B}(Z_c^{+}\to \ddot{I}{€}^{+}+c\bar{c})$ ($c\bar{c}=J/\ddot{I}ˆ$, $\ddot{I}{‡}_{c1}(1P)$, $\ddot{I}ˆ(2S)$)) and the product of Born cross section and branching fraction for $e^{+}{e}^{-}\to Z_c^{+}{Z}_c^{(\prime )-}$ ($\ddot{I}ƒ(e^{+}{e}^{-}\to Z_c^{+}{Z}_c^{(\prime )-})\times \mathcal{B}(Z_c^{+}\to \ddot{I}{€}^{+}+c\bar{c})$) at $\sqrt{s}$ = 10.52, 10.58, and 10.867 GeV are determined. Here, $Z_c$ refers to the $Z_c(3900)$ and $Z_c(4200)$ observed in the $\ddot{I}€J/\ddot{I}ˆ$ final state, the $Z_{c1}(4050)$ and $Z_{c2}(4250)$ in the $\ddot{I}€\ddot{I}{‡}_{c1}(1P)$ state, and the $Z_c(4050)$ and $Z_c(4430)$ in the $\ddot{I}€\ddot{I}ˆ(2S)$ state.

16 pages, 10 figures, 6 tables