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arXiv · hep-ex/0306013

Diffractive Photoproduction of J/psi Mesons with Large Momentum Transfer at HERA

H1 Collaboration
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Abstract

The diffractive photoproduction of J/psi mesons is measured with the H1 detector at the ep collider HERA using an integrated luminosity of 78 pb^-1. The differential cross section d sigma(gamma p -> J/psi Y) / d t is studied in the range 2 < |t| < 30 GeV^2, where t is the square of the four-momentum transferred at the proton vertex. The cross section is also presented as a function of the photon-proton centre-of-mass energy W in three t intervals, spanning the range 50 < W < 200 GeV. A fast rise of the cross section with W is observed for each t range and the slope for the effective linear Pomeron trajectory is measured to be alpha^\prime= -0.0135 \pm 0.0074 (stat.) \pm 0.0051 (syst.) GeV^-2. The measurements are compared with perturbative QCD models based on BFKL and DGLAP evolution. The data are found to be compatible with s-channel helicity conservation.

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H1 Collaboration. 2003-06-04. Diffractive Photoproduction of J/psi Mesons with Large Momentum Transfer at HERA. https://doi.org/10.1016/j.physletb.2003.06.056

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