Eur. Phys. J. C (1999) 6: 493-501
https://doi.org/10.1007/s100529800921

Tevatron-hera colour-octet charmonium anomaly versus higher-order QCD effects

¹ Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, D-80805, Munich, Germany
² II. Institut für Theoretische Physika, Universität Hamburg, Luruper Chaussee 149, D-22761, Hamburg, Germany

Received: 10 March 1998
Revised: 22 April 1998
Published online: 17 September 2013

Abstract

Approximately taking into account the higher-order effects due to multiple-gluon initial-state radiation, we extract from the latest Tevatron data of prompt J/ψ hadroproduction the leading colour-octet matrix elements within the nonrelativistic-QCD (NRQCD) factorization formalism proposed by Bodwin, Braaten, and Lepage. We find that the matrix elements which describe the formation of J/ψ mesons from colour-octet pairs in the angular-momentum states^2S+1 L _J = ¹ S ₀ and ³ P _J , with J = 0,1,2, which are responsible for the excess of the predicted cross section of inelastic J/ψ photoproduction over the existing HERA data at high values of the inelasticity variable z, are significantly reduced. We conclude that it is premature to proclaim a discrepancy between the Tevatron and HERA measurements of inclusive J/ψ production in the NRQCD framework. We also consider J/ψ mesons originating from the radiative feed down of promptly produced χcJ mesons.