Direct J/ψ and ψ' hadroproduction via fragmentation in the collinear parton model and kT-factorization approach

The pT spectra for direct J/ψ and ψ' 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 kT-factorization approach. We describe the Collider Detector at Fermilab data and obtain a good agreement between the predictions of the parton model and the kT-factorization approach. We perform the calculations using the relevant leading order in αs hard amplitudes and taking equal values of the long-distance matrix elements for both models