Neutrino Anarchy and Renormalization Group Evolution

TL;DR

This paper examines how renormalization group effects influence the neutrino anarchy hypothesis, showing that RG running can significantly alter the statistical distribution of neutrino mixing parameters and improve compatibility with observations.

Contribution

It provides the first detailed analysis of the stability of the neutrino anarchy hypothesis under RG evolution in type-I and inverse seesaw models.

Findings

RG effects tend to reduce mixing angles in inverse seesaw models

Dirac CP phase becomes closer to zero after RG running

Compatibility with observed mixing angles improves by 10-20% due to RG effects

Abstract

The observed pattern of neutrino mixing angles is in good agreement with the hypothesis of neutrino anarchy, which posits that Nature has chosen the entries of the leptonic mixing matrix at random. In this paper we investigate how stable this conclusion is under renormalization group effects. Working in the simplest type-I seesaw model and two variants of the inverse seesaw model we study how the statistical distributions of the neutrino mixing parameters evolve between the Grand Unification scale and the electroweak scale. Especially in the inverse seesaw case we find significant distortions: mixing angles tend to be smaller after RG running, and the Dirac CP phase tends to be closer to zero. The p-value describing the compatibility between the observed mixing angles and the anarchy hypothesis increases by 10-20%. This illustrates that RG effects are highly relevant for quantitative studies of the anarchy scenario.