Theoretical insights on nuclear double parton distributions

TL;DR

This paper provides a theoretical analysis of nuclear double parton distributions in pA collisions, deriving contributions from different nucleon interactions, verifying sum rules, and exploring implications for the EMC effect.

Contribution

It introduces a formal derivation of nuclear DPDs within the Light-Front approach, including sum rules and the first calculation for the deuteron using realistic wave functions.

Findings

DPS1 and DPS2 contributions are comparable but DPS1 is smaller.

Sum rules for nuclear DPDs are verified analytically.

EMC-like ratios suggest DPS may influence the EMC effect.

Abstract

In this paper, we address double parton scattering (DPS) in pA collisions. Within the Light-Front approach, we formally derive the two contributions to the nuclear double parton distribution (DPD), namely: DPS1, involving two partons from the same nucleon, and DPS2, where the two partons belong to different parent nucleons. We then generalize the sum rule for hadron DPDs to the nuclear case and analytically show how all contributions combine to give the expected results. In addition partial sum rules for the DPDs related to DPS1 and DPS2 mechanisms are discussed for the first time. The deuteron system is considered for the first calculation of the nuclear DPD by using a realistic wave function obtained from the very refined nucleon-nucleon AV18 potential, embedded in a rigorous Poincar\'e covariant formalism. Results are used to test sum rules and properly verify that DPS1 contribution compares with the DPS2 one, although smaller. We also introduce EMC-like ratios involving nuclear and free DPDs to address the potential role of DPS in understanding in depth the EMC effect.