$\mathbf {{{\mathit \eta}{(2100)}} }$ $\mathit I{}^{G}(\mathit J{}^{PC}) = 0{}^{+}(0{}^{-+})$

INSPIRE  
MASS ${\mathrm {(MeV)}}$ WIDTH ${\mathrm {(MeV)}}$ EVTS DOCUMENT ID TECN  COMMENT
$ 2050 {}^{+30}_{-24} {}^{+75}_{-26} $ $250 {}^{+36}_{-30} {}^{+181}_{-164}$ 1
ABLIKIM
2016N
 BES3 ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit K}^{+}}$ ${{\mathit K}^{-}}{{\mathit K}^{+}}{{\mathit K}^{-}}$
$ 2103 \pm50 $ $187 \pm75$ 586 2
BISELLO
1989B
 DM2 ${{\mathit J / \psi}}$ $\rightarrow$ 4 ${{\mathit \pi}}{{\mathit \gamma}}$
1  From a partial wave analysis of ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \phi}}{{\mathit \phi}}$ , for which the primary signal is ${{\mathit \eta}{(2225)}}$ $\rightarrow$ ${{\mathit \phi}}{{\mathit \phi}}$ , and that also finds significant signals for for ${}^{}0{}^{-+}$ phase space, ${{\mathit f}_{{0}}{(2100)}}$ , ${{\mathit f}_{{2}}{(2010)}}$ , ${{\mathit f}_{{2}}{(2300)}}$ , ${{\mathit f}_{{2}}{(2340)}}$ , and a previously unseen ${}^{}0{}^{-+}$ state ${{\mathit X}{(2500)}}$ (M = $2470$ ${}^{+15}_{-19}{}^{+101}_{-23}$ MeV, $\Gamma $ = $230$ ${}^{+64}_{-35}{}^{+56}_{-33}$ MeV).
2  ASTON 1981B sees no peak, has 850 events in Ajinenko+Barth bins. ARESTOV 1980 sees no peak.
References:
ABLIKIM 2016N
PR D93 112011 Observation of Pseudoscalar and tensor Resonances in ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \phi}}{{\mathit \phi}}$
BISELLO 1989B
PR D39 701 First Observation of Three Pseudoscalar States in the ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \rho}}{{\mathit \rho}}$ Decay