  A linked cluster expansion for the distorted one-body mixed density matrix is
obtained within the Glauber multiple scattering theory with correlated wave
functions. The nuclear transparency for 16O is calculated using realistic
central and non-central correlations. The convergence of the expansion is
investigated in the case of 4He for which the transparency and the distorted
momentum distributions are calculated to all order in the correlations using a
variational wave function obtained from realistic NN interactions. The
important role played by non central correlations is illustrated.
