2008/11/13 by B. Z. Kopeliovich, E. Levin, I. K. Potashnikova +2 · 12 citations
Physics and Astronomy · #Gluon #Hadron #High-Energy Particle Collisions Research #Nuclear physics #Nucleon #Particle physics #Particle physics theoretical and experimental studies #Parton #Physics #Quantum Chromodynamics and Particle Interactions #Quantum chromodynamics #Transverse plane #Unitarity #hep-ph
paper · pdf · doi:10.1103/physrevc.79.064906
published in Physical Review C 79(6) (American Institute of Physics) · 7 pages, 4 figures
arxiv created 2008/11/13 · openalex publication_date 2009/06/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Although at small Bjorken x gluons originated from different nucleons in a nucleus overlap in the longitudinal direction, most of them are still well separated in the transverse plane and therefore cannot fuse. For this reason the gluon density in nuclei cannot drop at small x below a certain bottom bound, which we evaluated in a model independent manner assuming the maximal strength of gluon fusion. We also calculated gluon shadowing in the saturated regime using the Balitsky-Kovchegov equation and found the nuclear ratio to be well above the unitarity bound. The recently updated analysis of parton distributions in nuclei [1], including BNL Relativistic Heavy Ion Collider (RHIC) data on high-pT hadron production at forward rapidities, led to strong gluon shadowing. Such strong shadowing and therefore the interpretation of the nuclear modification of the pT spectra in dA collisions at RHIC seem to be inconsistent with this unitarity bound.