Neutrino theory: open questions and future opportunities

TL;DR

This paper reviews the current understanding of neutrino masses, exploring various theoretical mechanisms, their testability, and recent experimental advances, highlighting open questions and future research directions in neutrino physics.

Contribution

It provides a comprehensive overview of mechanisms for generating neutrino masses and discusses their experimental and cosmological implications, emphasizing testability and future prospects.

Findings

High-scale seesaw models are less testable experimentally.

Low-scale and radiative mechanisms offer more accessible testing.

Recent experimental advances are promising for understanding neutrino origins.

Abstract

The subtitle of my talk is ``The quest for understanding the origin of neutrino masses''. After reviewing why the discovery of neutrino masses is also the discovery of New Physics, the substance of the talk details mechanisms for generating Majorana neutrino masses and implications for experimental searches and/or cosmology. I review high-scale seesaw, low-scale seesaw and radiative mechanisms, asking at every turn how testable the scenario is. While it is clear that determining the origin of neutrino masses -- knowing what Lagrangian to put into textbooks -- is a distant and ambitious goal, I end with experimental advances that we can reasonably hope for that would constitute progress.