Properties of CP Violation in Neutrino-Antineutrino Oscillations

TL;DR

This paper explores how neutrino-antineutrino oscillations can reveal Majorana CP-violating phases, providing theoretical formulas and analyzing their properties under different neutrino mass hierarchies.

Contribution

It derives the probabilities and CP asymmetries for neutrino-antineutrino oscillations in a three-flavor framework, highlighting the role of Majorana phases.

Findings

Majorana phases significantly affect CP asymmetries

CP asymmetries can exist without the Dirac phase

Distinct behaviors under normal and inverted hierarchies

Abstract

If the massive neutrinos are the Majorana particles, how to pin down the Majorana CP-violating phases will eventually become an unavoidable question relevant to the future neutrino experiments. We argue that a study of neutrino-antineutrino oscillations will greatly help in this regard, although the issue remains purely academic at present. In this work we first derive the probabilities and CP-violating asymmetries of neutrino-antineutrino oscillations in the three-flavor framework, and then illustrate their properties in two special cases: the normal neutrino mass hierarchy with m_1 = 0 and the inverted neutrino mass hierarchy with m_3 = 0. We demonstrate the significant contributions of the Majorana phases to the CP-violating asymmetries, even in the absence of the Dirac phase.