Nuclear matter spectral function in the Bethe-Brueckner-Goldstone approach

The microscopic many-body theory of the Nuclear Equation of State is discussed in the framework of the Bethe-Brueckner-Goldstone method. The expansion is extended up to the three hole-line diagrams contribution. Within the same scheme, the hole spectral function is calculated in nuclear matter to assess the relevance of nucleon-nucleon short-range correlations. The calculation is carried out by using several nucleon-nucleon realistic interactions. Results are compared with other approaches based on variational methods and transport theory. Discrepancies appear in the high-energy region, which is sensitive to short-range correlations, and are due to the different many-body treatment more than to the specific NN interaction used. Both nuclear matter Equation of State and spectral function appear to be dominated by two-body correlations.