Nuclear Physics Seminar with Alex Haber and Garrett King

"Unified Approach to In-Medium Beta Decay" presented by Alex Haber from Washington University in St. Louis

Beta decay in degenerate, dense nuclear matter is traditionally split into direct and modified Urca and computed separately in the Fermi surface approximation. In order to do so, very crude approximations for the internal nucleon propagator in modified Urca must be applied. In this talk I will present an idea for a unified approach to direct and modified Urca that relies on the optical theorem to connect the width of the nucleons and the neutrino to the beta decay rates we are computing. This will allow us to not only combine modified and direct Urca in a single computation, but also improve on these calculations in various aspects.

"Beta Decay and Muon Capture in Light Nuclei" presented by Garrett King from Washington University in St. Louis

Understanding electroweak interactions in nuclei is crucial for future fundamental physics searches. Neutrinoless double beta decay measurements and neutrino oscillation experiments rely on nuclear matrix elements and thus, to disentangle new physics signals from nuclear physics effects, an accurate understanding of the underlying nuclear dynamics is required. In this talk, I discuss the validation of one- and two-body electroweak current operators consistent with the Norfolk interaction —a high-quality local chiral interaction containing two- and three-nucleon forces— through quantum Monte Carlo calculations of nuclear matrix elements relevant to beta decay and muon capture. These matrix elements are used to make comparisons with readily available experimental data and to systematically analyze aspects of the model.