Partial wave analysis of J/ ψ →γγφ

Using a sample of ∼1010 J/ψ events collected by the BESIII detector at the BEPCII collider, a partial-wave analysis of the decay γγφ is performed to investigate the intermediate resonances in J/ψ→γR, R→γφ. Resonances including f1(1285), η(1405), f1(1420), f1(1510), f2(1525), X(1835), f2(1950), f2(2010), f0(2200), and ηc have been detected with statistical significance greater than 5σ. The product branching fractions B(J/ψ→γR,R→γφ) are reported, and the resonance parameters of η(1405) and X(1835) have been precisely determined. It seems likely that η(1405) and X(1835) act as the first - and second - excited states of η′, respectively. The observation of ηc→γφ holds great significance for the in depth study of charmonium properties. No evidence of η(1295), η1(1855) or X(2370) is found. The measured upper limits of relevant branching fraction products do not conflict with theoretical expectations for X(2370) as a pseudoscalar glueball and η1(1855) as a hybrid state.