Neutrino mass models by the 1000s!

Abstract

Abstract After putting the problem of neutrino mass generation in the context of physics beyond the standard model as a whole, I specialise to models of radiative Majorana neutrino masses and mixings. I spend most of the time summarising the results of a systematic classification and model-construction scheme based on opening up gauge-invariant ΔL = 2 effective operators constructed out of standard model fields. The focus is on tree-level openings of all operators up to mass dimension 11 using only exotic fields for the virtual states in the UV. This process produces renormalisable models that furnish mostly loop-level - that is to say radiative - Majorana neutrino mass models. I reference a searchable database authored by Gargalionis, and describe some of the general features of this large family of about 11,000 models. We will see that exotics such as scalar leptoquarks abound, and often lead to models of neutrino mass that can also address some or all of the current B-decay anomalies such R K(*) and R D (*) and the (g – 2) e,μ discrepancies.