Parton saturation and Npart scaling of semi-hard processes in QCD

Dmitri Kharzeev*, Eugene Levin, Larry McLerran

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

282 Scopus citations


We argue that the suppression of high pt hadrons discovered recently in heavy ion collisions at RHIC may be a consequence of saturation in the color glass condensate. We qualitatively and semi-quantitatively describe the data, in particular, the dependence upon the number of nucleon participants. We show that if parton saturation sets in at sufficiently small energy, then in nucleus-nucleus collisions at RHIC and LHC energies the cross sections of semi-hard processes should scale approximately with the number of participants, Npart. Our results provide a possible explanation of both the absence of apparent jet quenching at SPS energies and its presence at RHIC. Under the same assumption we predict that in semi-central and central pA (dA) collisions at collider energies the dependence of semi-hard processes on the number of participating nucleons of the nucleus will change to ∼ (NpartA)1/2. The forthcoming data on dA collisions will provide a crucial test of this description.

Original languageEnglish
Pages (from-to)93-101
Number of pages9
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Issue number1-2
StatePublished - 22 May 2003


FundersFunder number
U.S. Department of EnergyDE-AC02-98CH10886
German-Israeli Foundation for Scientific Research and DevelopmentI-620-22.14/1999
United States-Israel Binational Science Foundation9800276
Israel Academy of Sciences and Humanities
Israel Science Foundation


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