Effective comparison of neutrino-mass models

New physics in the lepton sector may account for neutrino masses, affect electroweak precision observables, induce charged-lepton flavor 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 (types 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.

Automated summary

New physics in the lepton sector has implications for neutrino masses, electroweak precision observables, charged-lepton flavor violation, and dipole moments. Effective field theory is a convenient formalism for comparing low-energy predictions of different models. By deriving the Wilson coefficients for representative models and considering various lepton observables, it becomes straightforward to understand the allowed parameter space for each model and discriminate between them. The Zee and leptoquark models are particularly relevant for explaining the muon g-2 anomaly.