The extraction of the nuclear sea-quark distribution and energy loss effect in a Drell–Yan experiment

Abstract

The next-to-leading order and leading order analysis are performed on the differential cross section ratio from Drell-Yan process. It is found that the effect of next-to-leading order corrections can be negligible on the differential cross section ratios as a function of the quark momentum fraction in the beam proton and the target nuclei for the current Fermilab and future lower beam proton energy. The nuclear Drell-Yan reaction is an ideal tool to study the energy loss of the fast quark moving through cold nuclei. In the leading order analysis, the theoretical results with quark energy loss are in good agreement with the Fermilab E866 experimental data on the Drell-Yan differential cross section ratios as a function of the momentum fraction of the target parton. It is shown that the quark energy loss effect has significant impact on the Drell-Yan differential cross section ratios. The nuclear Drell-Yan experiment at current Fermilab and future lower energy proton beam can not provide us with more information on the nuclear sea quark distribution.

Uncertainty due to quark energy loss in determining the nuclear sea quark distribution from nuclear Drell-Yan data

“…The available nuclear Drell-Yan data are in the form of ratios over deuterium and beryllium, R A/Be (x 1(2) ) for the Fermilab Experiment866, and R A/D (x 1(2) ) for the Fermilab Experiment772, respectively. The x 1 dependence of cross section rations R A 1 /A 2 (x 1 ) and R A/D (x 2 ) data, which is different from the results with E866 data [18] . In fact, the values of the parameter α (or β) in the quark energy loss expression should be the same for fitting the ratios R A 1 /A 2 (x 1 ) or R A 1 /A 2 (x 2 ) from the nuclear Drell-Yan experiment if the experimental data are sufficiently precise.…”

“…It is proved that there is quark energy loss effect in nuclear Drell-Yan reactions, which is an ideal tool to study the energy loss of the fast quark moving through cold nuclei. In the recent paper [18] , a next-to-leading order and a leading order analysis are performed of the differential cross section ratios from the proton-induced Drell-Yan reaction off nuclei. It is found that the next-to-leading order corrections can be negligible on the differential cross section ratios for the current Fermilab and future lower proton energy.…”

Nuclear medium effects in Drell–Yan process

“…We have also studied(not shown here) the dependence of the parameter α used in the expression given in Eq. (27) for energy loss, we have varied α in the range 0.5 < α < 3, corresponding to the range of values used in literature [24,25,44], for…”

The study of the incoming parton energy loss effect on the NLO nuclear Drell–Yan ratios

“…It is obvious that the differences between the calculated results for the leading order Drell-Yan ratios and that for the next-to-leading order are very small. The reason may be that the form of the differential cross section ratio as a function of the quark momentum fraction ( ( ) R x x x , , A A F 1 2 1 2 ) avoids the influence of the QCD next-to-leading order correction [31]. We have found that the comparisons with the E906, E866 and NA3 experimental data exhibit a clear disagreement with the corrections alone from the nPDF, especially for the E906 and NA3 measurements at the lower incident energy.…”