The intellectual merit of this project rests on its principal goal: to probe the fundamental physics of nuclei and neutrinos by exploiting the exciting synergy between nuclear physics and neutrino physics on the one hand, and the dynamics/nucleosynthesis of astrophysical environments on the other. The interrelated physics of neutrinos and strong interaction physics/nuclei is at the heart of current theories for the origin of the light nuclei and the baryon/lepton numbers in the early universe, the origin of the heavy nuclei in stellar collapse-based events, the dynamics of supernovae, and potentially even the dark matter/energy problems. Nuclear physics and nuclear astrophysics stand at the contact point of two great current trends in science: (1) the ongoing experimentally driven revolution in neutrino physics; and (2) the startling recent advances in the capabilities of observational astronomy, especially in cosmology. This represents a tremendous opportunity for advancing both fundamental neutrino/nuclear physics and astrophysics and cosmology through their interconnection. The work supported by this project will aim at exploiting this opportunity. In fact, the PI and his graduate students over the last three funding cycles have discovered a number of these connections between fundamental weak interaction/neutrino/nuclear physics and the frontiers of astrophysics, in early universe physics, the physics of gravitational collapse, nucleosynthesis, and especially the possible connections between neutrino ?avor transformation and dynamics/nucleosynthesis. This has proven to be an excellent training ground for graduate students (7 PhD's in 9 years, all of whom have positions in nuclear physics research, and 5 have tenured or tenure track positions) and undergraduates (6 REU undergraduates). This project will enable the continuing training of excellent students. Coupled with the PI's seminars/outreach and publications, this constitutes the broader impact of this project beyond the scientific product. Arguably, the mass-squared differences and vacuum mixing angles (save for 13) of the neutrinos are now measured. A key goal of this project is to assess and calculate the impact of this new knowledge on models for the physics of the early universe, gravitational collapse, and nucleosynthesis. Some neutrino properties, like the CP-violating phase(es) and 13 remain unmeasured. A goal here will be to assess the role of these quantities in astrophysical environments with an eye toward constraints. Ultimately, the full extent of the neutrino mass and mixing spectrum, especially regarding right-handed states remains mysterious. Because the cosmological parameters (e.g., as derived from the Cosmic Microwave Background (CMB) anisotopies) and neutrino properties are so tightly constrained, a positive result in the on-going mini-BooNE experiment, for example, could signal the existence of a light SU(2) singlet 'sterile' neutrino which mixes with active species. This might also signal the existence of a large net lepton number(s) as well as call for a radical overhall of existing models for stellar collapse, heavy element nucleosynthesis, the role of neutrinos in dark matter/energy, and the origin of the baryon number. Observations of Ultra Metal Poor halo stars recently have given us new insight into the r-process which challenge existing models (e.g., the solar system abundance pattern seems to be universal for nuclear masses > 100). The PI and his students will direct analytic and numerical calculations toward: (1) an understanding of active-active and active-sterile channel neutrino flavor transformation in the early universe as regards big bang nucleosynthesis and lepton number generation/destruction/limits, CMB derived neutrino mass limits, supernova shock re-heating, r-process nucleosynthesis, the supernova neutrino signal, and all with emphasis on insight into the newly discovered fixed point solution for the nonlinear neutrino-neutrino forward scattering 'background' potential in the active-active neutrino/antimeutrino conversion channel; (2) a further study of neutrino-nucleus interactions in stellar collapse/heavy element nucleosynthesis, including de-excitation of hot nuclei into neutrino pairs and neutrino capture-induced fission, as well as a consistent treatment of the relationship between the high temperature nuclear partition function and the weak strength distribution in nuclei; (3) studies directed toward better constraints on sterile neutrino dark matter from better knowledge of the physics of the QCD epoch in the early universe, from future x-ray observatories, and from the effects of these particles in post-supernova explosion neutron stars, especially the way in which the neutrino potentials which the govern de-coherence production of these heavy states evolve with time; (4) exploring the role of dynamical neutrino mass generation in cosmology; (5) studies of high neutron excess r-process nucleosynthesis with fission cycling.
