From nuclear structure to weak decays: Towards first principles calculations in medium-mass to heavy nuclei

Abstract:  Ab initio theoretical nuclear structure calculations including chiral two- and three-nucleon interactions have been very successful in predicting nuclear properties measured at radioactive ion beam facilities. The in-medium similarity renormalization group (IMSRG) is one of these ab initio methods. In the valence-space (VS) formulation, the VS-IMSRG provides from first principles effective Hamiltonians that can be handled with standard nuclear shell model techniques. This framework, therefore, is ideal to cover a wide range of medium-mass to heavy nuclei that can be studied with the shell model. In this seminar I will present recent VS-IMSRG developments leading to calculations for exotic argon, titanium, nickel and tin isotopes, as well as electromagnetic transitions. I will confront theoretical predictions with recent experiments performed at NSCL, RIBF, GANIL and ISOLDE. In addition, the VS-IMSRG can be extended to weak decays. I will discuss VS-IMSRG beta-decay calculations, where recent work shows that the "quenching" needed by conventional approaches to reproduce experimental Gamow-Teller half-lives is mostly avoided when complex nuclear correlations and meson-exchange currents are taken into account. Finally, I will also present some results on the very rare double-beta decays, including a possible connection to electromagnetic transitions.