Finite width effects on the azimuthal asymmetry in proton-nucleus collisions in the Color Glass Condensate

We perform a numerical analysis of the two particle azimuthal correlations at central rapidities generated in pA collisions within the framework of the Color Glass Condensate. We extend the standard computations to include the subeikonal corrections which stem from considering the finite longitudinal width of the dense target. For practical reasons, we only consider the next-to-next-to-eikonal corrections instead of using the all-order expressions for the inclusive two gluon production cross section. We show that the subeikonal terms that we account for in the two gluon yields contribute to both even and odd harmonics, the latter being absent in the standard Color Glass Condensate calculations performed at eikonal accuracy. Our analysis confirms the vanishing of the subeikonal effects with increasing collision energy and when going to forward rapidities, as expected. (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons .org /licenses /by /4 .0/). Funded by SCOAP3.

Automated summary

We numerically analyze the azimuthal correlations of two particles generated in pA collisions at central rapidities within the framework of the Color Glass Condensate. In our analysis, we consider the subeikonal corrections arising from the finite longitudinal width of the dense target. Our results show that the subeikonal terms contribute to both even and odd harmonics, unlike the standard Color Glass Condensate calculations at eikonal accuracy. Furthermore, we confirm the expected disappearance of subeikonal effects with increasing collision energy and forward rapidities.