出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：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
p
s = 17:4A GeV we nd 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,
p
s = 200A GeV, the e
ect 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.
