Year: 2009
Type: article
Abstract: 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-${p}_{T}$ hadron production at forward rapidities, led to strong gluon shadowing. Such strong shadowing and therefore the interpretation of the nuclear modification of the ${p}_{T}$ spectra in $dA$ collisions at RHIC seem to be inconsistent with this unitarity bound.
Source: Physical Review C
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1986402515