Observation of a ResonanceX(1835)inJ/ψ→γπ+π−<

Abstract

The decay channel J/ψ → γπ + π − η ′ is analyzed using a sample of 5.8 × 10 7 J/ψ events collected with the BESII detector. A resonance, the X(1835), is observed in the π + π − η ′ invariant mass spectrum with a statistical significance of 7.7σ. A fit with a Breit-Wigner function yields a mass M = 1833.7 ± 6.1(stat) ± 2.7(syst) MeV/c 2 , a width Γ = 67.7 ± 20.3(stat) ± 7.7(syst) MeV/c 2 and a

Status of X(1835) and pp¯ Interaction from Chiral Symmetry

“…The peak X(1835) is also observed in J/ψ → γπ + π − η [58], and this is consistent with the previous findings in J/ψ → γpp [1]. An updated analysis of J/ψ → γπ + π − η is performed in 2010 [59].…”

“…In fact, up to now, there is still no definite conclusion for the existence of X(1835) in ππη and more reliable (confirmative) results need to be explored on the experimental side [64]. Nevertheless, one experimental fact is clear: X(1835) is discovered in J/ψ → γη ππ by BES-III collaboration [58,59]. This supports the theoretical calculations by Ding et al [65] using the coherent state method.…”

“…Given the fact that Br(J/ψ → γX)Br(X → ππη ) ≈ 2.2 × 10 −4 [58], the corresponding theoretical result above is a factor of 10 smaller compared to the experiment, which seems somewhat disappointing, i.e., disfavoring the interpretation by baryonium. However, for us, this result suffers from large model dependence, especially for the determined coupling constant, which shows a large cutoff dependence, although the author chose 2.0 GeV ≤ Λ X ≤ 3.0 GeV as the cutoff region to do the numerical calculation (cf.…”

Study of η(1475) and X(1835) in radiative Ablikim1, Ачасов2, Ahmed3 et al. 2018Phys. Rev. DSelf Cite

“…Under the one-state assumption, the partial width relationship between its γρ and γϕ decay modes is predicted to be Γ γρ ∶Γ γϕ ≃ 3.8∶1 [10]. The Xð1835Þ was first observed by the BESII experiment in the ππη 0 [12] invariant mass spectrum and was recently confirmed with higher statistical significance by the BESIII collaboration [13]. It was also observed in the K 0 S K 0 S η invariant mass spectrum by BESIII [14].…”

Decay of the pseudoscalar glueball into scalar and pseudoscalar mesons

“…On the other hand, it is also possible that the pseudoscalar glueballG has a mass that is a bit lower than the lattice QCD prediction and that it has been already observed in the BESIII experiment where pseudoscalar resonances have been investigated in J=c decays [23]. In particular, the resonance Xð2370Þ, which has been clearly observed in the þ À 0 channel, represents a good candidate, because it is quite narrow ($ 80 MeV) and its mass lies just below the lattice QCD prediction.…”