CP violation in scattering of neutrinos on polarized proton target

TL;DR

This paper investigates how CP violation affects the azimuthal distribution of recoil protons in elastic muon neutrino scattering on polarized protons, proposing a model-independent method to detect CP-violating phases.

Contribution

It introduces a novel, model-independent analysis of CP violation effects in neutrino-proton scattering, focusing on azimuthal asymmetries and their detection.

Findings

Azimuthal asymmetry does not depend on neutrino mass.

Maximal asymmetry indicates CP-violating phase presence.

Method can distinguish neutrino interactions from background.

Abstract

In this paper, we analyze the elastic scattering of the muon neutrino beam on the polarized proton target (PPT), and predict how the existence of CP-violating phase between the complex vector V and axial A couplings of the left-chirality neutrinos affects the azimuthal dependence of the differential cross section. The neutrinos are assumed to be Dirac fermions with non-zero mass. We show that the azimuthal asymmetry of recoil protons does not depend on the neutrino mass and does not vanish even if $\beta_{VA} = 0$. The CP-breaking phase $\beta_{VA}$ could be detected by measuring the maximal asymmetry of the differential cross section. We also indicate the possibility of using the PPT to distinguish the detector background from the neutrino interactions. Our analysis is model-independent and the results are presented in a limit of infinitesimally small neutrino mass.