Ab initio take on the definition, meaning and usefulness of effective single-particle energies in (correlated!) nuclei

11h GANIL seminar room (105)

a coffee will be served 15mn before

The concept of single-nucleon shells dates back to the early days of nuclear physics and constitutes the basic pillar of the nuclear shell model and of our understanding of nuclear structure. This presentation will address the definition, the meaning, and the usefulness of effective single-particle energies (ESPEs) in doubly closed shell nuclei from the perspective of one-nucleon transfer reactions. Specifically, several points of interest will be discussed and illustrated through ab-initio coupled-cluster calculations of oxygen and calcium isotopes. Those points are (i) the impact of correlations on both ESPEs and one-nucleon separation energies, (ii) the error made by computing/extracting ESPEs approximately,  (iii) to which extent ESPEs are "observable" and (iv) to which extent observables, e.g. one-nucleon separation energies and the energy of the first excited 2+, are correlated with the size of the gap at the Fermi energy in the ESPE spectrum.