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Single-particle spectral function of the Λ hyperon in finite nuclei

Authors: Isaac Vidaña

Ref.: Nuclear Physics A 958, 48 (2017)

Abstract: The spectral function of the Λ hyperon in finite nuclei is calculated from the corresponding Λ self-energy, which is constructed within a perturbative many-body approach using some of the realistic hyperon-nucleon interactions of the Ju ̈lich and Nijmegen groups. Binding energies, wave functions and disoccupation numbers of different single-particle states are obtained for various hypernuclei from 5 He to 209Pb. The agreement between the calculated binding energies ΛΛ and experimental data is qualitatively good. The small spin-orbit splitting of the p−,d−,f− and g−wave states is confirmed. The discrete and the continuum contributions of the single-Λ spectral function are computed. Their appearance is qualitatively similar to that of the nucleons. The Z-factor, that measures the importance of correlations, is also calculated. Our results show that its value is relatively large, indicating that the Λ hyperon is less correlated than nucleons. This is in agreement with the results obtained by other authors for the correlations of the Λ in infinite nuclear matter. The disoccupation numbers are obtained by integrating the spectral function over the energy. Our results show that the contribution of the discrete part of the Λ self-energy is always much more smaller than the continuum one. This indicates that, in the production reactions of hypernuclei, the Λ hyperon is mostly formed in a quasi-free state.

DOI: 10.1016/j.nuclphysa.2016.11.002