2002/12/12 by P. Balbi, Balbi, P., Alberto Giovannini +2
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ph
paper · pdf · doi:10.48550/arxiv.hep-ph/0212168
21 pages, 6 diagrams, 8 figures
arxiv created 2002/12/12 · openalex publication_date 2002/12/12 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Following HERA experiments our interest is focused, in the present paper, on charmonium production in lepton-proton collisions. Inelastic J/ψelectroproduction is quite difficult to be measured due to the low rates of events; almost all experimental studies are indeed performed in photoproduction regime. J/ψresonance is considered as the product of the hadronization of a c c pair generated via boson-gluon fusion. The leading order contribution to the differential cross section, with respect to virtual photon-proton center of mass energy W and transferred four-momentum squared Q2, is written as the sum of two terms related to a colour singlet and a colour octet c c pair production respectively. This expression contains two-gluons contributions and depends on three parameters; two of them are related to the hadronization fractions in charmonium states for the c c pair (colour singlet and colour octet), while the third parameter takes into accout possible ``hot-spot'' effects. The values of these parameters are estimated by mean of a fit to the experimental data collected by H1 collaboration at HERA. By using different gluon densities, different sets of parameters are obtained, always with good fits.