Analysis of the \boldsymbole⁺ e^- → J/ψD D reaction close to the threshold concerning claims of a χ_c0(2P) state

2019/02/18 by Wang, En, Liang, Wei-Hong, Oset, Eulogio
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph)

paper · doi:10.48550/arxiv.1902.06461

Abstract

We analyze the DD mass distribution from a recent Belle experiment on the e⁺e^- → J/ψDD reaction, and show that the mass distribution divided by phase space does not have a clear peak above the DD threshold that justifies the experimental claim of a χ_c0(2P) state from those data. Then we use a unitary formalism with coupled channels D⁺D^-, D⁰D⁰, D_sD_s, and ηη, with some of the interactions taken from a theoretical model, and use the data to fix other parameters. We then show that, given the poor quality of the data, we can get different fits leading to very different DD amplitudes, some of them supporting a DD bound state and others not. The main conclusion is that the claim for the χ_c0(2P) state, already included in the PDG, is premature, but refined data can provide very valuable information on the DD scattering amplitude. As side effects, we warn about the use of a Breit-Wigner amplitude parameterization close to threshold, and show that the D_sD_s channel plays an important role in this reaction.

Related

• The nature and line shapes of charmonium in the e⁺e^- → DD reactions
• pΛ final-state interaction in the reactions e⁺e^- → K^- p Λ and J/ψ→ K^- p Λ
• The nature of X(3900) and recognition of open charm effects
• Competition of χ_c(2P) quarkonia and continuum in e⁺ e^- → e⁺ e^- D D
• Criterion for the Existence of the G(3900) Resonance