- th / 0 30 60 44 v 2 1 5 Ju n 20 03 Transparent Nuclei and Deuteron - Gold Collisions at RHIC ∗ March 2 , 2008

Abstract

Gribov’s inelastic shadowing makes nuclei more transparent and reduce nuclear cross sections, especially when QCD dynamics (color transparency) is at work. This effect steeply rising with energy has an important impact on the recent results for high-pT hadron production at RHIC. Only the shape of pT -dependence of the d−Au to pp ratio was measured, but the absolute value was calculated. Those calculations are subject to serious corrections: (i) the nuclear inelastic cross section should be considerably reduced due to inelastic shadowing which we evaluate in the light-cone color-dipole formalism. The large saturation effects proposed by Kharzeev-Levin-McLerran imply such a strong Gribov’s shadowing for the inelastic d − Au cross section, that the properly normalized measured ratio should agree with the suppression of high-pT hadrons predicted by this model; (ii) further reduction of the nuclear cross section is related to the specific triggering which misses diffractive excitations of the deuteron and gold. We employ the colordipole approach to evaluate the cross section of those channels; (iii) diffractive part should be subtracted from the proton-proton inelastic cross section as well, reducing it from 42mb down to 30mb. As a consequence, all experimental results which use this cross section for normalization should be revised. In particular, data for high-pT hadron suppression in gold-gold collisions must be renormalized by factor 1.4. ∗Based on lectures given by the author at Workshop on High pT Correlations at RHIC, Columbia University, May-June, 2003. 1

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Cite this paper

@inproceedings{Kopeliovich2003T, title={- th / 0 30 60 44 v 2 1 5 Ju n 20 03 Transparent Nuclei and Deuteron - Gold Collisions at RHIC ∗ March 2 , 2008}, author={Boris Z. Kopeliovich}, year={2003} }