• Nuclear, Particle, Astroparticle and Cosmology (NUPAC) Seminars

October 14, 2025 2:00 PM
PAIS 3205

Host:

Huaiyu Duan

Presenter:

Anson Kost (UNM)

Neutrinos are unique. They interact only weakly, passing through the Earth (and ourselves) without any interaction at all. However, in extreme astrophysical environments like supernovae and neutron star mergers, there can be so many neutrinos, packed so densely, that they interact with matter and even with each other. These collective neutrino oscillations are still not well understood. The natural starting point is the semiclassical equation of motion, the mean-field approximation. However, the short length and time scales of collective neutrino oscillations makes them too computationally difficult to include in simulations of, e.g., core-collapse supernovae. I will discuss two analytical approaches ("miscidynamics" and "flavomons") that aim to "factor out" the fast dynamics, leaving only the slow evolution of coarse-grained quantities. I will also discuss whether our starting point, the mean-field approximation, may not be satisfactory, since it ignores the fact that neutrinos can get entangled with each other. In particular, I will present new results of the "once-in-a-lifetime encounter" model and discuss the presence of quantum chaos in collective neutrino oscillations.