Energy Dependence of CP-Violation Reach for Monochromatic Neutrino Beam

TL;DR

This paper evaluates how the energy of monochromatic neutrino beams affects the ability to detect CP violation in neutrino oscillations, emphasizing the importance of SPS upgrades and baseline length.

Contribution

It analyzes the energy dependence of CP violation sensitivity using monochromatic neutrino beams from electron capture decay, comparing different accelerator configurations and baselines.

Findings

Higher SPS energy and longer baselines improve CP violation sensitivity.

Knowledge of |U(e3)| enhances the potential to detect CP violation.

Upgrading SPS to 1000 GeV is beneficial when combined with longer baselines.

Abstract

The ultimate goal for future neutrino facilities is the determination of CP violation in neutrino oscillations. Besides $| U(e3) | \ne 0$, this will require precision experiments with a very intense neutrino source and energy control. With this objective in mind, the creation of monochromatic neutrino beams from the electron capture decay of boosted ions by the SPS of CERN has been proposed. We discuss the capabilities of such a facility as a function of the energy of the boost and the baseline for the detector. We compare the physics potential for two different configurations: I) $\gamma=90$ and $\gamma=195$ (maximum achievable at present SPS) to Frejus; II) $\gamma=195$ and $\gamma=440$ (maximum achievable at upgraded SPS) to Canfranc. We conclude that the SPS upgrade to 1000 GeV is important to reach a better sensitivity to CP violation iff it is accompanied by a longer baseline. In both Setups, the gain in the CP violation sensitivity with a previous knowledge of $| U(e3) |$ is apparent.