Hybrid Textures of Majorana Neutrino Mass Matrix and Current Experimental Tests

Abstract

Motivated by recent measurements of a relatively large θ_{13} in the Daya Bay and RENO reactor neutrino experiments, we carry out a systematic analysis of the hybrid textures of Majorana neutrino mass matrix $M_ν$, which contain one texture zero and two equal nonzero matrix elements. We show that three neutrino masses (m_1, m_2, m_3) and three leptonic CP-violating phases (δ, ρ, σ) can fully be determined from two neutrino mass-squared differences (δm^2, Δm^2) and three flavor mixing angles (θ_{12}, θ_{23}, θ_{13}). Out of sixty logically possible patterns of $M_ν$, thirty-nine are found to be compatible with current experimental data at the 3σlevel. We demonstrate that the texture zero of $M_ν$ is stable against one-loop quantum corrections, while the equality between two independent elements not. Phenomenological implications of $M_ν$ for the neutrinoless double-beta decay and leptonic CP violation are discussed, and a realization of the texture zero and equality by means of discrete flavor symmetries is illustrated.

29 pages, 6 figures, more discussions and references added, to appear in Phys. Rev. D