Correlation effects on a propagation in nuclear matter

The propagation of a Λ hyperon in nuclear matter is studied within the Green's function formalism. The probability density for adding a Λ hyperon with momentum k to the correlated nuclear matter ground state is obtained from the complete energy dependence of the real and imaginary parts of the Λ self-energy. This self-energy incorporates the effects of short-range correlations induced by the hyperon-nucleon interaction and the strong coupling between ΛN and ΣN states which is known to be crucial for a correct determination of the Λ binding energy. The calculated spectral functions and quasi-particle parameters for the Λ are found to be qualitatively similar to corresponding results for correlated nucleons. In general, the Λ is less strongly correlated with the nuclear matter environment at k_F=1.36 fm^-1 than a nucleon, in agreement with empirical information from finite nuclei.