Neutrino Mass: The Present and the Future

TL;DR

This paper reviews the current evidence for neutrino mass, discusses key questions it raises, and explores the possibility of a four-neutrino spectrum that explains oscillations without sterile neutrinos.

Contribution

It introduces a model of four-neutrino spectra that accounts for neutrino oscillations without involving sterile neutrinos, challenging previous assumptions.

Findings

Evidence for neutrino mass is strong.

A four-neutrino spectrum can explain oscillations without sterile neutrinos.

The paper outlines future research directions.

Abstract

We argue that the evidence for neutrino mass is quite compelling. This mass raises a number of questions, which we enumerate, about neutrinos. Then we focus on one of these questions---the issue of the possible neutrino mass spectra. In particular, we explain that one can have a four-neutrino spectrum which does not require significant sterile-neutrino involvement in either the atmospheric or solar neutrino oscillations.