DirectJ/ψandψ′hadroproduction via fragmentation in the collinear parton model andkT-factorization approach

Abstract

The ${p}_{T}$ spectra for direct $J/\ensuremath{\psi}$ and ${\ensuremath{\psi}}^{\ensuremath{'}}$ hadroproduction at Fermilab Tevatron energy are calculated within the framework of the NRQCD formalism and the fragmentation model in the collinear parton model as well as in the ${k}_{T}$-factorization approach. We describe the Collider Detector at Fermilab data and obtain a good agreement between the predictions of the parton model and the ${k}_{T}$-factorization approach. We perform the calculations using the relevant leading order in ${\ensuremath{\alpha}}_{s}$ hard amplitudes and taking equal values of the long-distance matrix elements for both models.