The inelastic production of J/ψ mesons in ep collisions has been studied with the ZEUS detector at HERA using an integrated luminosity of 109 pb-1. The J/ψ mesons were identified using the decay channel J/ψ → μ+μ- The measurements were performed in the kinematic range 2 < Q2 < 80 GeV2, 50 < W < 250 GeV, 0.2 < z < 0.9 and -1.6 < Ylab < 1.3, where Q2 is the virtuality of the exchanged photon, W is the photon-proton centre-of-mass energy, z is the fraction of the photon energy carried by the J/ψ meson in the proton rest frame and Ylab is the rapidity of the J/ψ in the laboratory frame. The measured cross sections are compared to theoretical predictions within the non-relativistic QCD framework including colour-singlet and colour-octet contributions, as well as to predictions based on the κT-factorisation approach. Calculations of the colour-singlet process generally agree with the data, whereas inclusion of colour-octet terms spoils this agreement. © Springer-Verlag/Società Italiana di Fisica 2005.
European Physical Journal C
Chekanov, S.; Derrick, M.; Magill, S.; Miglioranzi, S.; Musgrave, B.; Repond, J.; Yoshida, R.; Mattingly, Margarita C. K.; Pavel, N.; Yagües Molina, A. G.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; de Pasquale, S.; Giusti, P.; Iacobucci, G.; Margotti, A.; Montanari, A.; Nania, R.; Palmonari, F.; Pesci, A.; and Polini, A., "Measurement of Inelastic J/ψ Production in Deep Inelastic Scattering at HERA" (2005). Faculty Publications. 2072.
Open access article retrieved March 18, 2021 from https://link.springer.com/content/pdf/10.1140/epjc/s2005-02346-2.pdf