The observation of neutrino flavor oscillations implies that neutrinos are massive particles, conclusive evidence of physics beyond the standard model (SM). The contribution of neutrino mass to the cosmological energy budget significantly influences the expansion history and growth of cosmological structure. Through measurements of the cosmic microwave background (CMB) and gravitational lensing, current and near-future experiments provide stringent constraints on several neutrino properties, such as the sum of the neutrino masses and the number of relativistic species in the early Universe.

The CPAC group at Argonne is engaged in numerous research activities dedicated to uncovering fundamental properties of neutrinos. On the experimental side, we are heavily involved in observational programs that have potential to dramatically enhance current constraints on neutrinos such as CMB-S4, LSST-DESC, and DESI. Neutrino physics is a central scientific aim of our simulation program based on the HACC cosmology code, which we use to generate high-precision predictions for the influence of neutrinos on large-scale cosmological structure.