Effective comparison of neutrino-mass models

TL;DR

This paper compares various neutrino-mass models using effective field theory, deriving Wilson coefficients, and analyzing their implications for lepton observables and anomalies like muon g-2 and B-meson decays.

Contribution

It provides a systematic EFT-based framework to compare neutrino-mass models and their phenomenological implications, including constraints and potential explanations for anomalies.

Findings

Different models have distinct origins for Weinberg and dipole operators.

Model constraints from lepton observables are systematically derived.

Certain models can address muon g-2 and B-meson decay anomalies.

Abstract

New physics in the lepton sector may account for neutrino masses, affect electroweak precision observables, induce charged-lepton flavour violation, and shift dipole moments. The low-energy predictions of different models are most conveniently compared within the formalism of effective field theory. To illustrate the benefits of this approach, we derive the Wilson coefficients for a set of representative models: the fermionic seesaw mechanisms (type I and III), the Zee model, and a minimal leptoquark model. In each case, the Weinberg and the dipole operators have qualitatively different origins. In parallel, we present the model-independent constraints on the Wilson coefficients coming from various lepton observables. We then show that it becomes straightforward to understand the allowed parameter space for each model, and to discriminate between them. The Zee and leptoquark models are suitable to address the muon $g-2$ anomaly. We also confront the models with the anomalies in the W-boson mass and semileptonic $B$-meson decays.