Observation of pseudoscalar and tensor resonances in $J/\ddot{I}ˆ\to {\hat{I}}^3\ddot{I}•\ddot{I}•$

Abstract

Based on a sample of $(1310.6\pm 10.5)\times 10^6$ $J/\ddot{I}ˆ$ events collected with the BESIII detector operating at the BEPCII storage ring, a partial wave analysis of the decay $J/\ddot{I}ˆ\to {\hat{I}}^3\ddot{I}•\ddot{I}•$ is performed in order to study the intermediate states. Results of the partial wave analysis show that the structures are predominantly $0^{-+}$ states. The existence of the $\hat{I}\cdot (2225)$ is confirmed, and its resonance parameters are measured. Two additional pseudoscalar states, the $\hat{I}\cdot (2100)$ with a mass of $2050_{-24}^{+30}{}_{-26}^{+75}$~MeV/$c^2$ and a width of $250_{-30}^{+36}{}_{-164}^{+181}$~MeV/$c^2$ and the $X(2500)$ with a mass of $2470_{-19}^{+15}{}_{-23}^{+101}$~MeV/$c^2$ and a width of $230_{-35}^{+64}{}_{-33}^{+56}$~MeV/$c^2$, are observed. In addition to these three pseudoscalar states, the scalar state $f_0(2100)$, and three tensor states, the $f_2(2010)$, $f_2(2300)$ and $f_2(2340)$, are observed in the process $J/\ddot{I}ˆ\to {\hat{I}}^3\ddot{I}•\ddot{I}•$. The product branching fractions $\mathcal{B}$($J/\ddot{I}ˆ\to {\hat{I}}^{3}X)\times \mathcal{B}(X\to \ddot{I}•\ddot{I}•)$ are reported.