Shadowing aspects of nuclear parton distributions

Various shadowing aspects of nuclear parton distributions are discussed in a parton-model framework. We explain existing x dependent data of F_2^A/F_2^D, then the model is applied to a flavor asymmetry \bar u-\bar d in a nucleus, to shadowing in valence-quark distributions, and to nuclear dependence of Q^2 evolution. First, we find that a finite nuclear \bar u-\bar d distribution could be possible due to nuclear interactions even in the flavor symmetric case in the nucleon (\bar u -\bar d=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^2 evolution \partial [F_2^{Sn}/F_2^C]/ \partial [\ln Q^2], 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^2 evolution