Physics Colloquium

**Tying it all together: connecting physics across the nuclear chart with ab initio theory**

Dr. Ragnar Stroberg

Research Assistant Professor

Physics Department, University of Washington

Developments effective field theory and non-perturbative many-body methods over the past decade have lead to the "ab initio revolution", and made it possible to compute nuclei from A=2 up to A~100 using the same nuclear interaction, without the need for phenomenological adjustments. This framework provides a path to meaningful theory error bars, which are essential for searches for new physics and for astrophysically relevant nuclei beyond what can be made in the lab. It also offers a way to understand some long-standing puzzles in nuclear physics, and to relate observables across the nuclear chart. In this colloquium, I will give a brief conceptual introduction to effective field theory and renormalization group ideas, with a focus on the valence-space in-medium similarity renormalization group (VS-IMSRG) approach, which has played an important role in the recent progress in ab initio theory. I will discuss applications of the VS-IMSRG to predictions of the limits of nuclear stability, the problem of quenching in beta decays, matrix elements for neutrinoless double beta decay searches. I will also present preliminary work on extending ab initio calculations up to 208Pb.

*Hosted by Prof. Surman*

*All interested persons are invited to attend remotely—email physics@nd.edu for information.*