Partial wave analysis of $J/\ddot{I}ˆ\to {\hat{I}}^3\hat{I}\cdot \hat{I}{\cdot }^{\prime }$

Abstract

Based on a sample of (10.09$\pm$0.04)$\times$10${}^9$ $J/\ddot{I}ˆ$ events collected with the BESIII detector operating at the BEPCII storage ring, a partial wave analysis of the decay $J/\ddot{I}ˆ\to {\hat{I}}^3\hat{I}\cdot \hat{I}{\cdot }^{\prime }$ is performed. An isoscalar state with exotic quantum numbers $J^{PC}=1^{-+}$, denoted as $\hat{I}{\cdot }_1(1855)$, has been observed for the first time with statistical significance larger than 19$\ddot{I}ƒ$. Its mass and width are measured to be (1855$\pm$9${}_{-1}^{+6}$)~MeV/$c^2$ and (188$\pm$18${}_{-8}^{+3}$)~MeV, respectively. The product branching fraction $\mathcal{B}(J/\ddot{I}ˆ$$\to$${\hat{I}}^3\hat{I}{\cdot }_1(1855)$$\to$${\hat{I}}^3\hat{I}\cdot \hat{I}{\cdot }^{\prime })$ is measured to be (2.70$\pm 0.41_{-0.35}^{+0.16})\times$10${}^{-6}$. The first uncertainties are statistical and the second are systematic. In addition, an upper limit on the branching ratio $\mathcal{B}(f_0(1710)$$\to$$\hat{I}\cdot \hat{I}{\cdot }^{\prime })$/$\mathcal{B}(f_0(1710)$$\to$$\ddot{I}€\ddot{I}€)$ is determined to be $1.61\times 10^{-3}$ at 90\% confidence level, which lends support to the hypothesis that the $f_0(1710)$ has a large glueball component.

17 pages, 21 figures. arXiv admin note: text overlap with arXiv:2202.00621