Colour-octet Contributions to J/psi Hadroproduction at Fixed Target Energies

Abstract

We investigate the integrated cross section for forward $\text{jpsi}$ production in proton-proton and pion-proton collisions at centre of mass energies upto 60 GeV. We find that colour-octet contributions to the cross section are crucially important, and their inclusion produces a very good description of the data. Since the values of non-perturbative matrix elements are fixed by other experiments, these predictions are parameter-free.

Comments: 7 pages vanilla LaTeX including one figure. Errors in eqs 3, 6, 8 corrected and other minor changes