Neutrino: chronicles of an aloof protagonist

Abstract

We give a brief account of the history of neutrino, and how that most aloof of all particles has shaped our search for a theory of fundamental interactions ever since it was theoretically proposed. We introduce the necessary concepts and phenomena in a non-technical language aimed at a physicist with some basic knowledge of quantum mechanics. In showing that neutrino mass could be the door to new physics beyond the Standard Model, we emphasize the need to frame the issue in the context of a complete theory, with testable predictions accessible to present and near future experiments. We argue in favor of the Minimal Left-Right Symmetric theory as the strongest candidate for such theory, connecting neutrino mass with parity breakdown in nature. This is the theory that led originally to neutrino mass and the seesaw mechanism behind its smallness, but even more important, the theory that sheds light on a fundamental question that touches us all: the symmetry between left and right.