The strong force at low energies: from exotic nuclei to fundamental symmetries

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One of the central challenges in nuclear physics is to understand and predict the properties of stable and exotic nuclei, for which three-nucleon (3N) forces are crucial and present a current frontier. This project will uniquely apply powerful many-body methods to strongly interacting nuclear systems, systematically implementing 3N forces in many-body calculations of medium-mass and heavier neutron-rich nuclei using similarity renormalization group (SRG) methods in momentum space and in-medium for consistent calculations of valence-shell interactions and electroweak operators. Chiral effective field theory (EFT) provides a systematic basis for nuclear forces including consistent many-body forces and theoretical uncertainties. With theoretical and computational advances, I am in a key position to connect the observations made in the laboratory to the underlying strong interactions governing the properties of nuclei. Applications of this work include predictions of exotic nuclei for rare-isotope beam experiments, such as those at TRIUMF, extreme neutron-rich matter in astrophysics, and the nuclear matrix elements of neutrinoless double-beta decay that probe the nature and mass scale of the neutrino.  I plan to systematically push these studies to heavy neutron-rich isotopes, reaching nickel, tin, and beyond, exploring structural evolution and limits of existence in medium-mass and heavy nuclei and make important first predictions with 3N forces in these regions.  A major future direction of this work will be going beyond semi-magic isotopic/isotonic chains. I have begun to access fluorine and neon isotopes, systematically exploring both proton and neutron driplines above 16O and 40Ca. This will present the first attempts to understand the island of inversion and r-process regions, based on NN+3N forces.  In the past year, I have made progress in applying the many-body formalism to the calculation of effective one- and two-body operators for electroweak transitions, including neutrinoless double-beta decay. First results have been published for light double-beta-decay nuclei 48Ca, 76Ge, and 82Se, where I found that the addition of these effects changed predictions of the neutrinoless double-beta-decay nuclear matrix element by 30-70%. I will apply this formalism combined with recent advances in two-body currents from chiral EFT to microscopically calculate M1, E2, and Gamow-Teller transitions in medium- and heavy-mass nuclei as well as neutrinoless double-beta-decay in heavy systems. Finally, I have recently developed a novel ab initio method, the in-medium SRG, for open-shell nuclei. This provides the first nonperturbative approach to valence-shell Hamiltonians that is feasible in practice. Very promising first results have been obtained with NN+3N forces for the oxygen isotopes and great synergy exits to explore the topics above with this method.