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Exclusive photoproduction of J / ψ in proton-proton and proton-antiproton scattering

2007; American Physical Society; Volume: 76; Issue: 9 Linguagem: Inglês

10.1103/physrevd.76.094014

1550-7998

Wolfgang Schäfer, Antoni Szczurek,

Quantum Chromodynamics and Particle Interactions

Protons and antiprotons at collider energies are a source of high-energy Weizs\"acker-Williams photons. This may open a possibility to study exclusive photoproduction of heavy vector mesons at energies much larger than possible at the HERA accelerator. Here we present a detailed investigation of the exclusive $J/\ensuremath{\psi}$ photoproduction in proton-proton (Relativistic Heavy Ion Collider, CERN LHC) and proton-antiproton (Tevatron) collisions. We calculate several differential distributions in ${t}_{1}$, ${t}_{2}$, $y$, $\ensuremath{\phi}$, as well as transverse momentum distributions of $J/\ensuremath{\psi}$'s. We discuss correlations in the azimuthal angle between outgoing protons or proton and antiproton as well as in the $({t}_{1},{t}_{2})$ space. Differently from electroproduction experiments, here both colliding beam particles can be a source of photons, and we find large interference terms in azimuthal-angle distributions in a broad range of rapidities of the produced meson. We also include the spin-flip parts in the electromagnetic vertices. We discuss the effect of absorptive corrections on various distributions. Interestingly, absorption corrections induce a charge asymmetry in rapidity distributions, and are larger for $pp$ reactions than for the $p\overline{p}$ case. The reaction considered here constitutes an important nonreduceable background in recently proposed searches for odderon exchange.