Beyond modified Urca: the nucleon width approximation for flavor-changing processes in dense matter

• DOI: 10.48550/arxiv.2406.13717
• Publication Date: 2024-06-19
• Authors: Mark Alford; Alexander Haber; Ziyuan Zhang
• Keywords: Dense matter

Flavor-changing charged current ("Urca") processes are of central importance in the astrophysics neutron stars. Standard calculations approximate Urca rate as sum two contributions, direct and modified Urca. Attempts to make more accurate have been impeded by an unphysical divergence at threshold density. In this paper we describe a systematically improvable approach where, simplest approximation, instead include imaginary part nucleon mass (nucleon width). The total is then obtained via straightforward generalization calculation, yielding results that agree with both densities where those approximations valid. At low densities, observe enhancement than order magnitude, important ramifications for star cooling other transport properties.