Dark radiation from neutrino mixing: Impact on cosmic microwave background and connection to Hubble tension

Dark radiation from neutrino mixing: Impact on cosmic microwave background and connection to Hubble tension

This paper studies models where dark radiation abundance changes over time due to mixing with neutrinos. The full equations are derived and implemented to study impact on cosmic microwave background and connection to Hubble tension. For strong coupling, tight mass prior gives minor impact, but larger mass range allows interpolation between standard model and extra dark radiation. For weak coupling, parameter spaces relevant for neutrino anomalies and Hubble tension are found.