Speaker
Description
Drell-Yan pair production off nuclei is an ideal tool to test the initial state nuclear effects occurring before a hard collision since no interaction in the final state is expected, either energy loss or absorption. We present for the first time a comprehensive study of the nucleus-to-nucleon production ratio (the nuclear modification factor) within the color dipole approach using the Green function formalism, which naturally incorporates for the color transparency and quantum coherence (QC) effects. We study a different onset of nuclear shadowing in various kinematical regions. At large values of the Feynman variable $x_F$ and dilepton invariant mass $M$ we include also a suppression factor due to restrictions caused by the energy conservation induced by multiple initial state interactions (ISI effects). The corresponding numerical results for the nuclear modification factor are compared with available data. Besides, we present a variety of predictions for the nuclear suppression as a function of $x_F$ and $M$ that can be verified by experiments at RHIC and LHC. The mixing of QC with ISI effects can be eliminated going to large values of the dilepton inveriant mass. Then predictions for the nuclear suppression is a direct manifestation for the onset of net ISI effects that can be verified by the future measurements.
