Systematic study of real photon and Drell-Yan pair production in p+A (d+A) interactions
1 FNSPE, Czech Technical University in Prague, Brehova 7, 115 19 Prague Czech Republic
2 Instituto de Fısica, Universidade Federal do Rio de Janeiro, Caixa Postal 68528 Rio de Janeiro, RJ 21941-972, Brazil
3 Department of Astronomy and Theoretical Physics, Lund University, SE-223 62 Lund, Sweden
4 High and Medium Energy Group, Instituto de Fisica e Matematica, Universidade Federal de Pelotas, Pelotas, RS, 96010-900, Brazil
5 Institute of Experimental Physics SAS, Watsonova 47, 04001 Kosice, Slovakia
a e-mail: email@example.com
Published online: 4 July 2016
We study nuclear effects in production of Drell-Yan pairs and direct photons in proton-nucleus collisions. For the first time, these effects are studied within the color dipole approach using the Green function formalism which naturally incorporates the color transparency and quantum coherence 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 transverse momentum pT, Feynman variable xF and invariant mass M of the lepton pair which can be verified by experiments at RHIC and LHC. We found that the nuclear suppression is caused predominantly by effects of quantum coherence (shadowing corrections) and by the effective energy loss induced by multiple initial state interactions. Whereas the former dominate at small Bjorken x2 in the target, the latter turns out to be significant at large x1 in the projectile beam and is universal at different energies and transverse momenta.
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