Nuclear Deformation Effects on Charmonium Suppression in Au+Au and U+U Collisions

TL;DR

This study examines how nuclear deformation influences charmonium suppression and flow in heavy-ion collisions, revealing that deformation significantly affects anisotropic flow but not overall yield suppression, especially in U+U collisions.

Contribution

It introduces a detailed modeling of nuclear deformation effects on charmonium observables using a modified Woods-Saxon distribution and transport equations.

Findings

Charmonium yield suppression is insensitive to nuclear deformation.

Anisotropic flow coefficients are sensitive to nuclear shape and collision orientation.

Deformation effects are more pronounced for excited charmonium states.

Abstract

We investigate the impact of intrinsic nuclear deformation and orientation on the yield suppression and momentum anisotropy of charmonia in Au+Au and U+U collisions at the Relativistic Heavy-Ion Collider. The anisotropic nucleon density within the nucleus is parameterized using a modified Woods-Saxon distribution, which is incorporated into the initial distributions of both the heavy quarkonia and the bulk medium energy density. The well-established Boltzmann-type transport equation is utilized to describe the dynamical evolution of quarkonium in the anisotropic bulk medium. Treating quarkonium suppression in Au+Au collisions as a baseline, we find that the momentum-integrated charmonium yield suppression is relatively insensitive to the initial nuclear geometry in deformed U+U collisions. In contrast, the anisotropic flow coefficients ($v_n$) of the charmonium is more sensitive to the nuclear deformation. Furthermore, these observables are also connected with the collision configuration, particularly when distinguishing between tip-tip and body-body orientations in U+U collisions at $\sqrt{s_{NN}} = 193$ GeV. This effect is more pronounced for the excited state due to its smaller binding energy and heightened sensitivity to the initial energy density of the hot QCD medium.