NUCLEAR-DEPENDENCE OF STRUCTURE FUNCTIONS IN COORDINATE SPACE

The momentum distributions of partons in bound nucleons are known to d epend significantly on the size of the nucleus. The Fourier transform of the momentum (x(Bj)) distribution measures the overlap between Fock components of the nucleon wave function which differ by a displacemen t of one parton along the light cone. The magnitude of the overlap thu s determines the average range of mobility of the parton in the nucleo n. By comparing the Fourier transforms of structure functions for seve ral nuclei we study the dependence of quark mobility on nuclear size. We find a surprisingly small nuclear dependence (< 2% for He, C and Ca ) for displacements t = z less than or similar to 2.5 fm, after which a nuclear suppression due to shadowing sets in. The nuclear effects ob served in momentum space for x(Bj) less than or similar to 0.4 can be understood as a reflection of only the large distance shadowing in coo rdinate space.