Correlation effects onΛpropagation in nuclear matter

Abstract

The propagation of a $\ensuremath{\Lambda}$ hyperon in nuclear matter is studied within the Green's function formalism. The probability density for adding a $\ensuremath{\Lambda}$ 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 $\ensuremath{\Lambda}$ self-energy. This self-energy incorporates the effects of short-range correlations induced by the hyperon-nucleon interaction and the strong coupling between $\ensuremath{\Lambda}N$ and $\ensuremath{\Sigma}N$ states which is known to be crucial for a correct determination of the $\ensuremath{\Lambda}$ binding energy. The calculated spectral functions and quasi-particle parameters for the $\ensuremath{\Lambda}$ are found to be qualitatively similar to corresponding results for correlated nucleons. In general, the $\ensuremath{\Lambda}$ is less strongly correlated with the nuclear matter environment at ${k}_{F}=1.36\phantom{\rule{0.3em}{0ex}}{\mathrm{fm}}^{\ensuremath{-}1}$ than a nucleon, in agreement with empirical information from finite nuclei.