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

At a next-to-leading order (NLO) calculation, the initial-state energy loss of the quark is investigated by means of the Drell–Yan experimental data including the new E906 measurements. Furthermore, the incoming gluon energy loss effect embedded in the Compton scattering subprocess of the nuclear Drell–Yan process is also examined. The NLO computations for Drell–Yan ratios are carried out with the SW quenching weights (provided by Salgado and Wiedemann to evaluate the probability distribution that quark (gluon) loses the energy), as well as the nuclear parton distributions (obtained by only fitting the existing experimental data on nuclear structure functions). It is found that the obtained calculations that consider the incoming quark energy loss agree well with the experimental data particularly for E906 data. In addition, the incoming gluon energy loss embodied in the primary NLO Compton scattering subprocess is not obvious, which may be due to the form of the Drell–Yan differential cross section ratio as a function of the quark momentum fraction ($R_{A_1/A_2}(x_1,x_2,x_F)$) minimizes the influence of the QCD NLO correction. (paper)