Near-threshold photoproduction of $$J/\psi $$ in two-gluon exchange model

Abstract

The near-threshold photoproduction of $$J/\psi $$ J / ψ is regarded as one golden process to unveil the nucleon mass structure, pentaquark state involving the charm quarks, and the poorly constrained gluon distribution of the nucleon at large x ($$>0.1$$ > 0.1 ). In this paper, we present an analysis of the current experimental data under a two-gluon exchange model, which shows a good consistency. Using a parameterized function form with three free parameters, we have determined the nucleonic gluon distribution at the $$J/\psi $$ J / ψ mass scale. Moreover, we predict the differential cross-section of the electroproduction of $$J/\psi $$ J / ψ as a function of the invariant mass of the final hadrons W, at EicC, as a practical application of the model and the obtained gluon distribution. According to our estimation, hundreds of $$J/\psi $$ J / ψ events can be detected per year on EicC near the threshold. Therefore, the relevant experimental measurements are suggested to be carried out on EicC.

Quantum anomalous energy effects on the nucleon mass

“…If ϕ(x) is a static constant B inside the nucleon, E a will be of order BV, where V is the effective volume in which the valence quarks are present. The static response of the composite gluon scalar ϕ in the nucleon state can be measured in the electro-production of heavy quarkonium on the proton [17,[36][37][38][39][40][41] or leptoproduction of heavy quarkonium at large photon virtuality [42]. The color dipole from the quarkonium will be an effective probe of the F 2 .…”

Energy-momentum tensor in QCD: nucleon mass decomposition and mechanical equilibrium

“…Even though the two-term and three-term mass decompositions do not contain the operator of the trace anomaly, it remains important to pursue attempts to measure (the gluon contribution to) the trace anomaly [68,69,[136][137][138][139][140][141][142][143][144][145][146][147]. Such measurements can help obtaining a more robust phenomenology of the quark and gluon contributions to the EMT trace.…”

Near threshold heavy vector meson photoproduction at LHC and EicC

“…In contrast, the amount of experimental data for low energies is scarce, in particular for energies 0123456789(). : V,-vol close to the threshold and ϒ production, and the description of the process in this energy range is still theme of intense debate [27][28][29][30][31][32][33][34][35][36][37][38][39]. A precise determination of the J/ and ϒ photoproduction at low energies has been motivated by several aspects.…”

“…Our predictions for the EicC will complement the studies performed in Refs. [34,35] by presenting the results for the total cross sections, rapidity and energy distributions derived considering distinct phenomenological models. Another goal is to investigate, for the first time, the near threshold vector meson production in fixed-target collisions at the LHC [59,60].…”