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arXiv · 1007.1913

Mutual boosting of the saturation scales in colliding nuclei

B. Z. Kopeliovich·H. J. Pirner·I. K. Potashnikova·Ivan Schmidt
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Abstract

Saturation of small-x gluons in a nucleus, which has the form of transverse momentum broadening of projectile gluons in pA collisions in the nuclear rest frame, leads to a modification of the parton distribution functions in the beam compared with pp collisions. The DGLAP driven gluon distribution turns out to be suppressed at large x, but significantly enhanced at x<<1. This is a high twist effect. In the case of nucleus-nucleus collisions all participating nucleons on both sides get enriched in gluon density at small x, which leads to a further boosting of the saturation scale. We derive reciprocity equations for the saturation scales corresponding to a collision of two nuclei. The solution of these equations for central collisions of two heavy nuclei demonstrate a significant, up to several times, enhancement of Q_{sA}^2, in AA compared with pA collisions.

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B. Z. Kopeliovich, H. J. Pirner, I. K. Potashnikova, Ivan Schmidt. 2010-07-12. Mutual boosting of the saturation scales in colliding nuclei. https://doi.org/10.1016/j.physletb.2011.02.018

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