Speaker
Description
Weak interaction (Urca) processes govern neutrino emission, chemical equilibration, and bulk viscosity in neutron stars and their mergers. Standard treatments inconsistently combine direct and modified Urca processes, but suffer from divergencies near the direct Urca threshold and are difficult to extend to finite temperature and strong magnetic fields. In this talk, I will present the Nucleon Width Approximation (NWA), a systematically improvable framework that provides a unified description of Urca processes across the direct Urca threshold while avoiding any unphysical divergences. I will then discuss the application of this framework to magnetized nuclear matter, demonstrating how enhanced weak interaction rates modify flavor equilibration, reduce relaxation times, and increase bulk viscosity in magnetic fields relevant to neutron star mergers.