Leptonic CP violation in a two parameter model

Samina S. Masood, Salah Nasri, Joseph Schechter

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


We further study the "complementary" ansatz, Tr(Mν)=0, for a prediagonal light Majorana type neutrino mass matrix. Previously, this was studied for the CP conserving case and the case where the two Majorana type CP violating phases were present but the Dirac type CP violating phase was neglected. Here we employ a simple geometric algorithm which enables us to "solve" the ansatz including all three CP violating phases. Specifically, given the known neutrino oscillation data and an assumed two parameter (the third neutrino mass m3 and the Dirac CP phase δ) family of inputs we predict the neutrino masses and Majorana CP phases. Despite the two parameter ambiguity, interesting statements emerge. There is a characteristic pattern of interconnected masses and CP phases. For large m3 the three neutrinos are approximately degenerate. The only possibility for a mass hierarchy is to have m3 smaller than the other two. A hierarchy with m3 largest is not allowed. Small CP violation is possible only near two special values of m3. Also, the neutrinoless double beta decay parameter is approximately bounded as 0.020eV<|mee|<0.185eV. As a by-product of looking at physical amplitudes we discuss an alternative parametrization of the lepton mixing matrix which results in simpler formulas. The physical meaning of this parametrization is explained.

Original languageEnglish
Article number093005
Pages (from-to)1-10
Number of pages10
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number9
Publication statusPublished - May 1 2005
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)


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