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We review the production of high-mass lepton pairs in fixed-target
experiments, including both Drell-Yan (DY) and heavy quarkonium production
[J/ψ, ψ′, ϒ(1S), ϒ(2S), and
ϒ(3S)]. In recent years, DY data have become standard input to the
determination of parton density distributions. DY data have recently yielded
the first measurement of the x dependence of the
,
asymmetry of the proton. Similar to the observations in deeply inelastic
scattering, precision measurements of the nuclear dependence of the
proton-induced DY process exhibit shadowing at small target momentum fraction,
x2. There is, however, no evidence of enhanced DY production
from nuclear targets. Mean transverse momenta of DY pairs are observed to
increase with target mass. These data, analyzed within a new theoretical
framework, provide an estimation of the energy loss of fast quarks in nuclear
matter. In contrast to the DY process, there are large nuclear effects in the
production of all quarkonia. These effects show strong dependence on
pt and xF but do not scale with
x2. Statistically less precise measurements of D meson
(open-charm) production at small xF are consistent with no
nuclear dependence.
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