Nucleons in the Medium and their Collective Motion

Dr. Panagiota Papakonstantinou (host Dickhoff), Institute for Basic Science Rare Isotope Science Project, Daejeon, South Korea
January 25, 2018 at 11:00 am
241 Compton
Event Description 

Ab initio nuclear theory has seen spectacular advances in recent years, thanks to innovations related to many-body and computational methods and the determination of bare and in-medium nuclear interactions beyond the two-body level. The power of the new approaches has been demonstrated by different groups in several studies of light and medium-mass nuclei and isospin-asymmetric matter. They generally provide a good description of nuclear ground-state properties and low-energy spectra, with almost no free parameters.

Collective excitations of heavy nuclei near the particle-emission threshold and up to the giant-resonance region are of much interest: Their energies, strengths, and damping mechanisms are largely determined by the nuclear equation of state, they facilitate astrophysically important reactions, and they provide insights into oscillations in other finite quantum systems. However, they remain inaccessible to strictly ab initio approaches. Therefore, our understanding of them is to a large extent phenomenological and involves crucial uncertainties.

In this talk I will discuss computationally feasible paths to heavy nuclei and to collective phenomena starting from realistic interactions. First, I will review an ongoing effort to assess the performance of modern pre-diagonalized interactions within the random-phase approximation (RPA) and extensions thereof, in particular the Second RPA. The results highlight the role of the three-nucleon force. Then I will argue for a comprehensive many-body method including explicit ground-state correlations. Finally, I will present a complementary effort to encode the effects of many-nucleon forces and correlations in a novel nuclear energy-density functional with excellent prospects for describing neutron-rich matter and related phenomena.

Coffee: 10:45 am, 241 Compton