We discuss nuclear broadening of the intrinsic transverse momentum of partons in the initial state, and its influence on the pt distribution of prompt photons. Comparing to WA98 data from Pb+Pb collisions at vs = 17.4A GeV we find evidence for the presence of nuclear broadening at high pt in this hard process. Below pt ~ 2.7 GeV the photon distribution is due to small momentum transfer processes. At RHIC energy, s = 200A GeV, the effect of intrinsic transverse momentum on the spectrum of prompt photons is less prominent. Below pt = 2 - 3 GeV the contribution from large momentum transfers flattens out, and we expect that region to be dominated by soft contributions.
|Journal||Proceedings of Science|
|State||Published - 2001|
|Event||2001 International Europhysics Conference on High Energy Physics, HEP 2001 - Budapest, Hungary|
Duration: 12 Jul 2001 → 18 Jul 2001