Nuclear, Particle, and Weak Interaction Physics of the Big Bang and Stellar Collapse

University Of California-San Diego, La Jolla CA

Investigators

Abstract

The research supported in this Project will provide insights into how atomic nuclei and elementary particles and radiation behave in the conditions of extreme temperature and density found in the cosmos. This research will seek to use these insights to provide important clues about the nature of elementary particles, the mysterious neutrinos in particular, and about how the elements are synthesized in nature, for example, the heaviest elements in the fiery interiors of collapsing stars or colliding neutron stars, and the lightest in the first seconds in the history of the universe. In turn, these considerations could yield clues about new physics, clues that may complement insights gleaned from terrestrial experiments. The calculations to be done in this project will involve honing humanity's fundamental theory of nature, i.e., Quantum Mechanics, into a tool capable of modeling the behavior of neutrinos and atomic nuclei in the extreme environments of the cosmos. Another key product of this Project will be the training of young nuclear physicists, at both the graduate and undergraduate levels. The research supported in this Project will be directed toward probing the fundamental physics of neutrinos and nuclei by exploiting the intersection of exciting new developments in nuclear physics and neutrino physics on the one hand, with the explosion of new data and insights from the advent of multi-messenger astronomy and precision cosmology on the other. A key issue in this enterprise will be studying how neutrinos interact in dense matter and how these interactions may cause these particles to change their flavors (e.g., electron type neutrinos changing to tau type and vice versa). This can be a fiercely nonlinear problem because the flavor content of the neutrino component in part determines how neutrino flavors change! Research in this project will target (1) Understanding and modeling nonlinear neutrino flavor evolution and assessing the impact of this process on compact objects (collapsing stellar cores; merging binary neutron stars) dynamics and nucleosynthesis; (2) Using the insights from these and other considerations to turn our models of, and observational constraints on compact object environments and the early universe into insights into beyond standard model physics, dark matter, and dark sector physics; (3) Understanding nuclear structure, neutrino-nucleus interactions, nuclear partition functions, and nuclear weak strength distributions in high temperature environments. This project advances the objectives of "Windows on the Universe: the Era of Multi-Messenger Astrophysics", one of the 10 Big Ideas for Future NSF Investments. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.