  By means of two different parametrizations of quark energy loss and the
nuclear parton distributions determined only with lepton-nuclear deep inelastic
scattering experimental data, a leading order phenomenological analysis is
performed on the nuclear Drell-Yan differential cross section ratios as a
function of the quark momentum fraction in the beam proton and target nuclei
for E772 experimental data. It is shown that there is the quark energy loss
effect in nuclear Drell-Yan process apart from the nuclear effects on the
parton distribution as in deep inelastic scattering. The uncertainties due to
quark energy loss effect is quantified on determining nuclear sea quark
distribution by using nuclear Drell-Yan data. It is found that the quark energy
loss effect on nuclear Drell-Yan cross section ratios make greater with the
increase of quark momentum fraction in the target nuclei. The uncertainties
from quark energy loss become bigger as the nucleus A come to be heavier. The
Drell-Yan data on proton incident middle and heavy nuclei versus deuterium
would result in an overestimate for nuclear modifications on sea quark
distribution functions with neglecting the quark energy loss. Our results are
hoped to provide good directional information on the magnitude and form of
nuclear modifications on sea quark distribution functions by means of the
nuclear Drell-Yan experimental data.
