Shadowing Aspects of Nuclear Parton Distributions

Various shadowing aspects of nuclear parton distributions are discussed in a partonmodel framework. We explain existing x dependent data of F 2 /F 2 , then the model is applied to a flavor asymmetry ū − d̄ in a nucleus, to shadowing in valence-quark distributions, and to nuclear dependence of Q evolution. First, we find that a finite nuclear ū−d̄ distribution could be possible due to nuclear interactions even in the flavor symmetric case in the nucleon (ū − d̄=0). Second, it is indicated that valence-quark shadowing could be used for discriminating among various shadowing models. Third, we find that nuclear dependence of Q evolution ∂[F Sn 2 /F 2 ]/∂[lnQ], which was found by NMC, is essentially understood by modification of parton distributions in nuclei. However, higher-twist effects in nuclear interactions could be tested by studying the details of the nuclear Q evolution.