A possible determination of the quark radiation length in cold nuclear matter

TL;DR

This paper presents theoretical predictions for Drell-Yan production in proton-nucleus collisions, aiming to use experimental data to measure the quark radiation length in cold nuclear matter and distinguish between nuclear shadowing and energy loss effects.

Contribution

It introduces a detailed calculation including NLO effects and nuclear medium effects, proposing a method to determine the quark radiation length in cold nuclear matter.

Findings

Drell-Yan production is sensitive to initial-state energy loss.

Predictions show measurable attenuation at high Feynman x_F.

Results suggest potential to determine the quark radiation length.

Abstract

We calculate the differential Drell-Yan production cross section in proton-nucleus collisions by including both next-to-leading order perturbative effects and effects of the nuclear medium. We demonstrate that dilepton production in fixed target experiments is an excellent tool to study initial-state parton energy loss in large nuclei and to accurately determine the stopping power of cold nuclear matter. We provide theoretical predictions for the attenuation of the Drell-Yan cross section at large values of Feynman $x_F$ and show that for low proton beam energies experimental measurements at Fermilab's E906 can clearly distinguish between nuclear shadowing and energy loss effects. If confirmed by data, our results may help determine the quark radiation length in cold nuclear matter $X_0 \sim 10^{-13}$ m.