Inelastic photoproduction of J/ψ mesons at HERA

C Adloff, Yves Coppens, John Dowell, Peter Faulkner, Yves Fleming, John Garvey, Carrie Johnson, Ian Kenyon, David Lamb, Paul Newman, Syed Rizvi, Paul Thompson, Ethan-Etienne Woehrling

Research output: Contribution to journalArticle

60 Citations (Scopus)

Abstract

An analysis of inelastic photoproduction of J/psi mesons is presented using data collected at the ep collider HERA corresponding to an integrated luminosity of above 80 pb(-1), Differential and double I <P-t/psi(2) <differential cross sections are measured in a wide kinematic region: 60 <W-gammap <260 GeV, 1 p(t,psi)(2) <60 GeV2 and 0.05 <z <0.9. where z is the fraction of the energy of the exchanged photon transferred to the J/psi meson in the rest frame of the target proton. Cross sections at z less than or similar to 0.3 are presented for the first time. Theoretical calculations within the Colour Singlet Model at NLO for direct photon processes are shown to give a good description of the data in the medium z region (0.3 <z <0.9) up to the highest p(t,psi)(2) values. A calculation using a k(t) factorisation approach in LO in the Colour Singlet Model is also able to describe these data. The data in the full z range are also compared to LO calculations within a non-relativistic QCD framework including colour octet and colour singlet contributions for direct and resolved photons. It seems possible to reconcile data and theory with modest contributions from colour octet processes. The polarisation of the J/psi meson is measured as a function of z and p(t,psi) and is reasonably described by the theoretical predictions.
Original languageEnglish
Pages (from-to)25-39
Number of pages15
JournalEuropean Physical Journal C
Volume25
DOIs
Publication statusPublished - 1 Jan 2001

Fingerprint

Dive into the research topics of 'Inelastic photoproduction of J/ψ mesons at HERA'. Together they form a unique fingerprint.

Cite this