CP violation in scattering of neutrinos on polarized proton target

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.