Oscillation Physics with a Neutrino Factory

TL;DR

This paper discusses the development of advanced neutrino experiments, including neutrino factories, to precisely measure neutrino mixing parameters and explore CP violation, which could reveal physics beyond the Standard Model.

Contribution

It introduces the concept of a neutrino factory with a muon storage ring as a powerful tool for comprehensive neutrino studies and CP violation detection.

Findings

Neutrino factories offer the largest reach for CP violation detection.

Extensions of conventional beams can observe $ u_ o u_e$ transitions.

Beta beams provide pure electron-neutrino sources for advanced experiments.

Abstract

A generation of neutrino experiments have established that neutrinos mix and probably have mass. The mixing phenomenon points to processes beyond those of the Standard Model, possibly at the Grand Unification energy scale. A extensive sequence of of experiments will be required to measure precisely all the parameters of the neutrino mixing matrix, culminating with the discovery and study of leptonic CP violation. As a first step, extensions of conventional pion/kaon decay beams, such as off-axis beams or low-energy super-beams, have been considered. These could yield first observations of $\nu_\mu \to \nu_e$ transitions at the atmospheric frequency, which have not yet been observed, and a first measurement of $\theta_{13}$. Experiments with much better flux control can be envisaged if the neutrinos are obtained from the decays of stored particles. One such possibility is the concept of beta beams provided by the decays of radioactive nuclei, that has been developed within the context of these studies. These would provide a pure (anti-)electron-neutrino beam of a few hundred MeV, and beautiful complementarity with a high-intensity, low-energy conventional beam, enabling experimental probes of T violation as well as CP violation. Ultimately, a definitive and complete set of measurements would offered by a Neutrino Factory based on a muon storage ring. This powerful machine offers the largest reach for CP violation, even for very small values of $\theta_{13}$.