2021/01/13 by Keiichi Kimura, Kimura, Keiichi, Akira Takamura +1 · 1 citation
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Neutrino Physics Research #Particle physics theoretical and experimental studies
paper · pdf · doi:10.48550/arxiv.2101.05101
openalex publication_date 2021/01/13 · openalex created_date 2021/01/18 · openalex updated_date 2026/07/28
In three generations or more, we derive the oscillation probabilities of both Dirac and Majorana neutrinos relativistically by using the Dirac equation. We present various oscillation probabilities for including wrong-helicity neutrinos, right-handed neutrinos, and anti-neutrinos. We summarize the relations between these probabilities. As neutrinos have finite mass, there are two components for each chirality corresponding to positive and negative helicities. We show that the probability is different for each component even if neutrinos have the same chirality. The probabilities derived by the relativistic equation depend on not only the mass squared differences but also the absolute masses of neutrinos. Besides, the new CP phases appear in the probabilities of oscillations with chirality-flip. These new CP phases are equivalent to the Majorana CP phases in the case of Majorana neutrinos. We investigate the CP dependence of oscillation probabilities in vacuum. There are no direct CP violation in να↔ νβc oscillations even if the flavors, α and β, are different as in the same as two generations. In other words, the difference between the CP-conjugate probabilities vanishes. However, in three generations or more, the sine terms of new CP phases appear in the probabilities in addition to the cosine terms. This is different from the result obtained in two generations. Furthermore, the zero-distance effect does not appear in our formulation.