Research in Theoretical Nuclear and Neutrino Physics

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

Exploring the origin, evolution and the structure of the visible matter is an ongoing quest of modern science. The lightest elements are formed during the first minutes after the Big Bang, the epoch known as the Big Bang Nucleosynthesis (BBN). The BBN epoch and the proceeding evolution of the stars until they go supernova produce elements up to iron. Most of the elements heavier than iron are thought to be produced by the capture of neutrons on seed nuclei. Possible sites of the rapid neutron capture process (r-process) include matter evaporated from the surface of a hot neutron star formed following a supernova explosion, the merging of two neutron stars (recently observed for the first time), and accretion disks in gamma-ray bursts. Irrespective of the precise details of the elements-formation process, one needs an abundance of neutrons over protons. All environments listed above also contain a very large number of neutrinos, which control the ratio of neutrons to protons. This project will explore the interplay between neutrino properties and the formation of elements using tools from nuclear physics and astrophysics, as well as experimental and observational data. This project will contribute to the description of neutrino transport in the r-process sites by solving the many-body equations describing collective oscillations of neutrinos, which are emergent nonlinear flavor evolution phenomena instigated by neutrino-neutrino interactions in astrophysical environments with sufficiently high neutrino densities. The goal is to bring together our theoretical and computational efforts with the optical observations of the abundances of chemical elements to explain where in the cosmos these elements are formed. The PI and his students will explore properties of neutrinos such as masses, mixings, and dipole moments and calculate their capture cross sections to facilitate this goal. 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.