Cronin effect vs. geometrical shadowing in d+Au collisions at RHIC

Multiple initial state parton interactions in p(d) + Au collisions are calculated in a Glauber-Eikonal formalism. The convolution of perturbative QCD parton-nucleon cross sections predicts naturally the competing pattern of low-p(T) suppression due geometrical shadowing, and a moderate-p(T) Cronin enhancement of hadron spectra. The formal equivalence to recent classical Yan-Mills calculations is demonstrated, but our approach is shown to be more general in the large x > 0.01 domain because it automatically incorporates the finite kinematic constraints of both quark and gluon processes in the fragmentation regions, and accounts for the observed spectra in elementary pp --> pi X processes in the RHIC energy range, roots similar to 20-200 GeV. The Glauber-Eikonal formalism can be used as a baseline to extract the magnitude of dynamical shadowing effects from the experimental data at different centralities and pseudo-rapidities. (C) 2004 Elsevier B.V. All rights reserved.