Parton energy loss in cold nuclei

TL;DR

This paper investigates how parton energy loss in cold nuclear matter affects Drell-Yan dilepton production, using a high-twist formalism and gluon density data, with implications for understanding nuclear effects in high-energy collisions.

Contribution

It introduces a formalism linking parton energy loss to the jet transport parameter and evaluates its impact on Drell-Yan spectra in proton-nucleus collisions.

Findings

Energy loss effects are negligible at 800 GeV energy in Fermilab data.

Predicted suppression of Drell-Yan spectra is significant at 120 GeV.

The jet transport parameter relates to the local gluon density of the medium.

Abstract

Within the generalized high-twist factorization formalism, we express the contribution from multiple parton scattering and induced gluon radiation to the DY dilepton spectra in terms of nuclear modified effective beam quark distribution function. We show that beam quark energy loss is characterized by jet transport parameter $\hat{q}$, which is related to the local gluon density of the medium. Using the value of $\hat{q}$ determined from the deeply inelastic scattering (DIS) data, we evaluate the nuclear modification factor in Drell-Yan process in p+A collisions. Effects of parton energy loss in the DY spectra are found negligible in the Fermilab experimental data at $E_{\rm lab}=800$ GeV relative to parton shadowing while the predicted suppression of DY spectra are significant at $E_{\rm lab}=120$ GeV.