Local-equilibrium theory of neutrino oscillations

TL;DR

This paper develops a new theoretical framework for neutrino oscillations, incorporating turbulent flavor-wave viscosity and analyzing flavor instabilities in astrophysical environments.

Contribution

It introduces the concept of turbulent flavor-wave viscosity and generalizes the linear analysis for neutrino flavor dispersion without small coherence assumptions.

Findings

Derived a new flavor-wave dispersion relation.

Developed techniques for including turbulence effects in miscidynamics.

Hypothesized constraints on flavor thermalization due to local oscillation invariants.

Abstract

Miscidynamics describes coarse-grained neutrino transport under the assumption that flavor mixing is in local equilibrium. Here we introduce the concept of turbulent flavor-wave viscosity and develop techniques for including it in miscidynamics. This extension of the theory is necessary when neutrinos develop weak flavor instabilities as a result of astrophysical driving. The flavor-wave dispersion relation is obtained using a new and more general form of linear analysis, which does not require small flavor coherence. Flavor-wave transport is then approximated using wave kinetics and geometric optics. We hypothesize that the dynamical emergence of local oscillation invariants restricts the extent of flavor thermalization. In this view, flavor evolution is sculpted by both entropy-increasing and order-promoting factors.