CP Violation in Predictive Neutrino Mass Structures

TL;DR

This paper investigates CP violation effects in specific neutrino mass matrices, analyzing their implications for neutrino oscillations and how high-dimensional operators can realize these structures.

Contribution

It introduces two new neutrino mass matrix textures with zero elements, derived from high-dimensional operators, and explores their CP violation characteristics and experimental implications.

Findings

Neutrino mass spectrum in normal ordering with specific lightest mass range.

Complete determination of parameters in one mass matrix texture.

Calculation of CP asymmetries in neutrino-antineutrino oscillations.

Abstract

We study the CP violation effects from two types of neutrino mass matrices with (i) $(M_\nu)_{ee}=0$, and (ii) $(M_\nu)_{ee}=(M_\nu)_{e\mu}=0$, which can be realized by the high dimensional lepton number violating operators $\bar \ell_R^c\gamma^\mu L_L (D_\mu \Phi)\Phi^2$ and $\bar \ell_R^c l_R (D_\mu{\Phi})^2\Phi^2$, respectively. In (i), the neutrino mass spectrum is in the normal ordering with the lightest neutrino mass within the range $0.002\,{\rm eV}\lesssim m_0\lesssim 0.007\,{\rm eV}$. Furthermore, for a given value of $m_0$, there are two solutions for the two Majorana phases $\alpha_{21}$ and $\alpha_{31}$, whereas the Dirac phase $\delta$ is arbitrary. For (ii), the parameters of $m_0$, $\delta$, $\alpha_{21}$, and $\alpha_{31}$ can be completely determined. We calculate the CP violating asymmetries in neutrino-antineutrino oscillations for both mass textures of (i) and (ii), which are closely related to the CP violating Majorana phases.