Leptonic unitarity triangles and effective mass triangles of the Majorana neutrinos

摘要

Given the best-fit results of six neutrino oscillation parameters, we plot the Dirac and Majorana unitarity triangles (UTs) of the 3 x 3 lepton flavor mixing matrix to show their real shapes in the complex plane. The connections of the three Majorana UTs with neutrino-antineutrino oscillations and neutrino decays are explored, and the possibilities of right or isosceles UTs are discussed. In the neutrino mass limit of m(1) -> 0 or m(3) -> 0, which is definitely allowed by current data, we show how the six triangles formed by the effective Majorana neutrino masses < m >(alpha beta) (for alpha, beta = e, mu, tau) and their corresponding component vectors look like in the complex plane. The relations of such triangles to the Majorana phases and to the lepton-number-violating decays H++ -> alpha(+)beta(+) in the type-II seesaw mechanism are also illustrated. (C) 2016 Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3).