High-pTpion and kaon production in relativistic nuclear collisions

High-$p_T$ pion and kaon production is studied in relativistic proton-proton, proton-nucleus, and nucleus-nucleus collisions in a wide energy range. Cross sections are calculated based on perturbative QCD, augmented by a phenomenological transverse-momentum distribution of partons (“intrinsic $k_T”).\mathrm{}$ An energy dependent width of the transverse-momentum distribution is extracted from pion and charged hadron production data in proton-proton/proton-antiproton collisions. Effects of multiscattering and shadowing in the strongly interacting medium are taken into account. Enhancement of the transverse-momentum width is introduced and parameterized to explain the Cronin effect. In collisions between heavy nuclei, the model overpredicts central pion production cross sections (more significantly at higher energies), hinting at the presence of jet quenching. Predictions are made for proton-nucleus and nucleus-nucleus collisions at relativistic heavy ion collider energies.