UNC-CH Physics and Astronomy Colloquium

Walter Pettus, University of Washington

“Weighing a Ghost: The Quest to Measure the Neutrino Mass”

The ghostly neutrinos remain the only fundamental fermions whose masses are unknown. Neutrino oscillation measurements definitively demonstrate neutrinos have mass, breaching the Standard Model of Particle Physics, but cannot determine that mass scale. The most sensitive searches to date have placed limits on the neutrino mass, indicating they are at least six orders of magnitude lighter than the next fermion. If neutrinos possess the unique property of being their own antiparticles, this vast scale difference is a clue to the new physics of their mass generation mechanism.

I will review the status of experiments to measure the neutrino mass scale, with particular emphasis on laboratory probes. Project 8 is an experimental program developing next-generation sensitivity to the neutrino mass through measurement of the kinematic beta endpoint, a model-independent probe of the mass scale. Complementary to this technique are searches for neutrinoless double beta decay, where I will detail the 76Ge program, advancing from the currently operating Majorana Demonstrator to the LEGEND experiment in preparation.