Change of confinement scale in nuclei: Predictions for structure functions confront electroproduction data

We confront our explanation of the ``European Muon Collaboration effect,'' in which the quark confinement scale increases in going from a free nucleon to nucleus, with a new electroproduction experiment off several nuclear targets. The change of confinement size is attributed to the overlap of nucleons in nuclei which increases with nuclear density. A change of confinement scale modifies the quark and gluon distribution functions and we compute, in leading order in QCD, its effects for a series of different nuclei. New, precise electron scattering measurements at SLAC agree well with these predictions for 0.2<x<0.7, supporting the postulate that the confinement size increases with nuclear density.