Shadowing in multiparton proton–deuteron collisions
B. Blok (Department of Physics, Technion-Israel Institute of Technology, 32000, Haifa, Israel); M. Strikman (Physics Department, Penn State University, University Park, PA, USA)
We study the screening effect for the multiparton interactions (MPI) for protonâdeuteron collisions in the kinematics where one parton belonging to the deuteron has small x1 , so the leading twist shadowing is present, while the second parton ( x2 ) is involved in the interaction in the kinematics where shadowing effects are small. We find that the ratio of the shadowing and the impulse approximation terms is approximately a factor of 2 larger for MPI than for the single parton distributions. We also calculate the double parton antishadowing (DPA) contribution to the cross section due to the independent interactions of the partons of the projectile proton with two nucleons of the deuteron and find that shadowing leads to a strong reduction of the DPA effect. For example, for the resolution scale Q12â¼4 Â GeV2 of the interaction with parton x1 we find that shadowing reduces the DPA effect by â¼ 30Â %. It is argued that in the discussed kinematics the contribution of the interference diagrams, which correspond to the interchange of partons between the proton and neutron, constitutes only a small correction to the shadowing contributions.
