Parametrization of nuclear parton distributions

Optimum nuclear parton distributions are obtained by analyzing available experimental data on electron and muon deep inelastic scattering (DIS). The distributions are given at Q^2=1 GeV^2 with a number of parameters, which are determined by a chi^2 analysis of the data. Valence-quark distributions are relatively well determined at medium x, but they are slightly dependent on the assumed parametrization form particularly at small x. Although antiquark distributions are shadowed at small x, their behavior is not obvious at medium x from the F_2 data. The gluon distributions could not be restricted well by the inclusive DIS data; however, the analysis tends to support the gluon shadowing at small x. We provide analytical expressions and computer subroutines for calculating the nuclear parton distributions, so that other researchers could use them for applications to other high-energy nuclear reactions.