Parton distributions in nuclear systems

Quark distribution functions in the nuclear medium are calculated by using an effective quark theory of QCD. We mainly concentrate on the flavor dependence of the in-medium quark distributions, and discuss the following interesting applications: (1) The EMC effect for parity-violating deep inelastic scattering of charged leptons on nuclear targets: Here we make predictions for the spin asymmetries, which are relevant to future experiments. (2) An explanation of the NuTeV anomaly in deep inelastic scattering of neutrinos on nuclear targets: Here we point out that the medium modifications of parton distribution functions can explain a large part of the so called NuTeV anomaly, which was observed in 2002 by using an iron target.