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Systematic analysis of the incoming quark energy loss in cold nuclear matter
The investigation into the fast parton energy loss in cold nuclear matter is
crucial for a good understanding of the parton propagation in hot-dense medium.
By means of four typical sets of nuclear parton distributions and three
parametrizations of quark energy loss, the parameter values in quark energy
loss expressions are determined from a leading order statistical analysis of
the existing experimental data on nuclear Drell-Yan differential cross section
ratio as a function of the quark momentum fraction. It is found that with
independence on the nuclear modification of parton distributions, the available
experimental data from lower incident beam energy rule out the incident-parton
momentum fraction quark energy loss. Whether the quark energy loss is linear or
quadratic with the path length is not discriminated. The global fit of all
selected data gives the quark energy loss per unit path length {\alpha} =
1.21\pm0.09 GeV/fm by using nuclear parton distribution functions determined
only by means of the world data on nuclear structure function. Our result does
not support the theoretical prediction: the energy loss of an outgoing quark is
three times larger than that of an incoming quark approaching the nuclear
medium. It is desirable that the present work can provide useful reference for
the Fermilab E906/SeaQuest experiment
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