New and trivial CP symmetry for extended A(4) flavor

Autor(es)

Nishi, C. C.

• Tipo de documento: Artigo Científico
• Fonte: PHYSICAL REVIEW D; v. 93, n. 9, p. 19-pg., 2016-05-16.

Resumo

The combination of nu(mu)-nu(tau) exchange together with CP conjugation in the neutrino sector (known as CP mu tau symmetry or mu tau reflection) is known to predict the viable pattern. theta(23) = 45 degrees, a maximal Dirac CP phase, and trivial Majorana phases. We implement such a CP symmetry as a new CP symmetry in theories with A(4) flavor. The implementation in a complete renormalizable model leads to a new form for the neutrino mass matrix that leads to further predictions: a normal hierarchical spectrum with a lightest mass and m(beta beta) (0 nu 2 beta) of only few meV, and either nu(1) or nu(2) has opposite CP parity. An approximate L-mu-L-tau symmetry arises naturally and controls the flavor structure of the model. The light neutrino masses are generated by the extended seesaw mechanism with six right-handed neutrinos (RHNs). The requirement of negligible one-loop corrections to light neutrino masses, the validity of the extended seesaw approximation, and not too long-lived beyond-the-Standard-Model states to comply with big bang nucleosynthesis essentially restricts the parameters of the model to a small region: three relatively light right-handed neutrinos at the GeV scale, heavier neutrinos at the electroweak scale, and Yukawa couplings smaller than the electron Yukawa. Such small Yukawa couplings render these RHNs unobservable in terrestrial experiments. (AU)

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