1997/03/10 by Bernd A. Kniehl, Gustav Kramer
Physics and Astronomy · #Computer science #Fragmentation (computing) #HERA #High-Energy Particle Collisions Research #Meson #Nuclear physics #Octet #Particle physics #Particle physics theoretical and experimental studies #Physics #Programming language #Quantum Chromodynamics and Particle Interactions #Quantum chromodynamics #hep-ex #hep-ph
paper · pdf · doi:10.1016/s0370-2693(97)01126-x
published as Phys.Lett. B413 (1997) 416-421 · 10 pages (Latex), 3 figures (Postscript)
arxiv created 1997/03/10 · openalex publication_date 1997/11/01 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We study J/psi photoproduction via fragmentation at next-to-leading order in the QCD-improved parton model, using the nonrelativistic factorization formalism proposed by Bodwin, Braaten, and Lepage. We consider direct and resolved photoproduction of prompt J/psi mesons and chicJ mesons radiatively decaying to J/psi+gamma, taking into account the formation of both color-singlet and color-octet c anti-c states. Adopting the values of the long-distance color-octet matrix elements extracted from fits to prompt-J/psi data recently taken at the Fermilab Tevatron, we predict that measurements of J/psi photoproduction at DESY HERA should show a distinctive excess over the expectation based on the color-singlet model at small values of the inelasticity variable z. This is complementary to the expected enhancement at z close to 1 due to the color-octet contribution to photon-gluon fusion.