Multiple scattering and pT broadening at RHIC energies
WoS ID: 000173799700104
Scopus ID: 0037060605
In ultrarelativistic heavy-ion collisions, in the 2 GeV< p(perpendicular to) < 6 GeV transverse momentum region, the soft and semi-hard multiple scattering of the incoming nucleons in the nuclear medium results in the broadening of the expected hadronic (e.g. pion) p(perpendicular to) spectra relative to proton-proton (pp) collisions. Thus, higher transverse-momentum regions are populated than in pp collisions. In a perturbative QCD based calculation we include the intrinsic transverse momentum (k(perpendicular to)) of the partons in the nucleon (determined from pp collisions), augmented by the extra broadening obtained via a systematic analysis of proton-nucleus (pA) collisions in the energy range 17< roots < 39 AGeV. The original polynomial spectra are modified, and a nearly exponential spectrum appears in the region 2less than or similar to p(perpendicular to) less than or similar to 3.5 GeV. At present RHIC energies (roots =130 AGeV), the slope of the calculated spectra is reminiscent of that of fluid-dynamical descriptions, but lacks any thermal origin. We determine and discuss the size of the modifications originating in multiple scattering, which lead to this state of affairs.