TEVATRON - HERA Colour - Octet Charmonium Anomaly Versus Higher - Order QCD E ects

Approximately taking into account the higher-order e ects due to multiple-gluon initial-state radiation, we extract from the latest Tevatron data of prompt J= hadroproduction the leading colour-octet matrix elements within the nonrelativisticQCD (NRQCD) factorization formalism proposed by Bodwin, Braaten, and Lepage. We nd that the matrix elements which describe the formation of J= mesons from colour-octet c c pairs in the angular-momentum states LJ = 1S0 and 3PJ , with J = 0; 1; 2, which are responsible for the excess of the predicted cross section of inelastic J= photoproduction over the existing HERA data at high values of the inelasticity variable z, are signi cantly reduced. We conclude that it is premature to proclaim a discrepancy between the Tevatron and HERA measurements of inclusive J= production in the NRQCD framework. We also consider J= mesons originating from the radiative feed down of promptly produced cJ mesons. PACS numbers: 13.60.-r, 13.85.-t, 13.85.Ni, 14.40.Lb Supported by Bundesministerium f ur Forschung und Technologie, Bonn, Germany, under Contract 05 7 HH 92P (5), and by EU Program Human Capital and Mobility through Network Physics at High Energy Colliders under Contract CHRX{CT93{0357 (DG12 COMA).