Observation of pseudoscalar and tensor resonances in $J/ψ\rightarrow γϕϕ$

Abstract

Based on a sample of $(1310.6 \pm 10.5) \times 10^{6}$ $J/ψ$ events collected with the BESIII detector operating at the BEPCII storage ring, a partial wave analysis of the decay $J/ψ\rightarrow γϕϕ$ 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 $η(2225)$ is confirmed, and its resonance parameters are measured. Two additional pseudoscalar states, the $η(2100)$ 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 $J/ψ\rightarrow γϕϕ$. The product branching fractions ${\cal B}$($J/ψ\rightarrow γX)\times{\cal B}(X\rightarrow ϕϕ)$ are reported.