Nuclear shapes from the In-Medium Similarity Renormalization Group

The In-Medium Similarity Renormalization Group (IMSRG) is one of a group of computationally efficient many-body methods that have extended first-principles calculations of nuclei to nuclei as heavy as the tin isotopes. Moreover, it has allowed forays toward doubly open-shell nuclei, where intrinsic deformations arise. This is achieved in two complementary ways, either by direct calculations based on intrinsically deformed and angular-momentum projected reference states, e.g., from Generator Coordinate Method calculations, or by deriving valence-space Hamiltonians and operators for use in traditional nuclear configuration interaction calculations. I will present results for ground- and excited-state observables from both approaches, and discuss their implications for the current state of the IMSRG and related many-body methods. I will also briefly touch upon efforts to refine the nuclear interactions and transition operators, derived from chiral Effective Field Theory, which serve as inputs to our calculations. This document is composed of an abstract and the slides of the presentation. (author)