The study of gluon energy loss in cold nuclear matter from $J/\psi$ production

TL;DR

This paper investigates gluon energy loss in cold nuclear matter affecting $J/$ suppression in p-A collisions, using experimental data and nuclear PDFs to extract the transport coefficient and assess the role of energy loss across different energies.

Contribution

It provides the first extraction of the gluon transport coefficient in cold nuclear matter from experimental data, highlighting the significance of gluon energy loss in $J/$ suppression.

Findings

Gluon energy loss significantly impacts $J/$ suppression at E866 and RHIC energies.

The transport coefficient for gluons is similar to that for light and heavy quarks.

Nuclear modifications at LHC are dominated by nuclear PDFs, with minimal energy loss effects.

Abstract

The energy loss effects of the incident quark, gluon and the color octet $c\bar{c}$ on $J/\psi$ suppression in p-A collisions are studied by means of the experimental data at E866, RHIC and LHC energy. By the Salgado-Wiedemann (SW) quenching weights and the recent EPPS16 nuclear parton distribution functions together with nCTEQ15, we extract the transport coefficient for the gluon energy loss from the E866 experimental data in the middle $x_{F}$ region ($0.20<x_{F}<0.65$). It is found that the difference between the values of the transport coefficient for light quark, gluon and heavy quark in the cold nuclear matter is very small. The theoretical results modified by the parton energy loss effects are consistent with the experimental data for E866 and RHIC energy, and the gluon energy loss plays a remarkable role on $J/\psi$ suppression in a broad variable range. Since the corrections of the nuclear parton distribution functions in the $J/\psi$ channel are significant at LHC energy, the nuclear modification due to the parton energy loss is minimal. It is worth noting that we use CEM at leading order to compute the p-p baseline, and the conclusion in this paper is CEM model dependent.