Probe the color screening in proton-nucleus collisions with complex potentials

TL;DR

This study uses a time-dependent Schrödinger equation with complex potentials to analyze how color screening affects charmonium suppression in proton-nucleus collisions at LHC energies, highlighting the importance of the imaginary potential part.

Contribution

It introduces a quantum mechanical approach with complex potentials to model charmonium evolution in pA collisions, emphasizing the role of imaginary parts in describing experimental suppression data.

Findings

Color screening is weak near the deconfinement transition.

Imaginary potential component is essential for matching experimental results.

Weak screening scenario aligns better with observed suppression patterns.

Abstract

Color screening and parton inelastic scattering modify the heavy-quark antiquark potential in the medium that consists of particles from quantum chromodynamics (QCD), leading to suppression of quarkonium production in relativistic heavy-ion collisions. Due to small charm/anti-charm ($c\bar{c}$) pair production number in proton-nucleus (pA) collisions, the correlation between different $c\bar{c}$ pairs is negligible, which makes the Schr\"odinger equation viable for tracking the evolution of only one $c\bar{c}$ pair. We employ the time-dependent Schr\"odinger equation with in-medium $c\bar{c}$ potential to study the evolution of charmonium wave functions in the hydrodynamic like QCD medium produced in pA collisions. We explore different parametrizations of real and imaginary parts of $c\bar{c}$ potential and calculate the nuclear modification factors ($R_{\rm pA}$) of $J/\psi$ and $\psi(2S)$ in $\sqrt{s_{NN}}=5.02$ TeV energy p-Pb collisions at Large Hadron Collider (LHC). Comparing a strong and a weak screening scenario with experimental data in this approach, we arrive at the conclusion that the color screening is weak at temperature close to deconfined phase transition. Moreover, the imaginary part of the potential is crucial to describe the experimental data which is consistent with widely studied semi-classical approaches where the dissociation rates are essential.