Emergent Large Lepton Mixing from Neutrino Refraction in Dark Matter

TL;DR

This paper introduces a new mechanism where neutrino refraction in ultralight dark matter causes the observed large lepton mixing angles, linking neutrino physics with dark matter and predicting environment-dependent oscillation effects.

Contribution

It proposes that neutrino refraction in dark matter backgrounds dynamically generates large lepton mixing angles from CKM-like fundamental mixing, without new flavor symmetries.

Findings

Neutrino oscillation effects depend on dark matter environment.

The model naturally explains quark-lepton mixing disparity.

Testable predictions for neutrino experiments.

Abstract

We propose a novel origin for the disparity between quark and lepton flavor mixing based on the refractive nature of neutrino masses. We postulate that the fundamental mixing in both the quark and lepton sectors is CKM-like, together with tiny vacuum neutrino masses, while the observed PMNS mixing matrix emerges dynamically from coherent forward scattering of neutrinos on an ultralight dark matter background. The resulting in-medium Hamiltonian rotates CKM mixing angles into large effective lepton mixings, naturally realizing quark--lepton complementarity without invoking new flavor symmetries. This framework links neutrino mass generation, flavor mixing, and dark matter, and predicts environment-dependent neutrino oscillation effects testable in current and future experiments.