**On Neutrino CP-Violation Idea **

Primarysuggestive qualitative ideas are especially important in basic frontierphysics. As examples, Einstein’s thought experiment on space-time connection inspecial relativity, equivalence principle in General relativity and others.

Themodern Standard Model is in need of a reliable flavor theory with CP-violation.An appropriate suggestive qualitative idea for CP-violating flavor degree offreedom is welcome. It seems that such idea exists, it can be outlined here.

In theSM, there is a universal leading by data bimaximalapproximation for all Dirac elementary particle (charged leptons and quarks) masshierarchy and neutrino mixing hierarchy quantities. We concentrate on neutrinomixing and likely needed here CP-violation.

Bimaximalapproximation is a distinguished one, especially by its two exact symmetries –geometric type SO(3) mixing symmetry and CP symmetry. But if CP symmetry isviolated in Nature, there must be already a related first stage quantity in theneutrino bimaximal approximation. In the SM, neutrino CP-violation is describedby nonzero imaginary part of the product Im [sinθ_{13 }exp(i d_{CP})] = (sinθ_{13}sind_{CP}) inthe Pontecorvo-Maki-Nakagava-Sakata mixing matrix. That first stage quantity inthe bimaximal approximation may be maximal CP-phase d_{CP} = 90o at θ_{13 }= 0, and vacuumfluctuations of the angle θ_{13} would produce vacuum CP-violating fluctuations.

_{13}= ~8.5o is not zero but small, the necessary condition for observable CP-violationis that Dirac CP-phase d

_{CP }should not be small. Because bimaximal neutrinomixing is the leading approximation of the realistic one, the requirement oflarge realistic Dirac phase follows from a feasible requirement of maximal firststage phase value d

_{CP}at bimaximal approximation. It does not produce observableCP effects at this approximation, but it calls for large realistic Dirac phase d

_{CP}< ~ 90

^{o}and nonzero reactor angle θ

_{13}> 0. Boththose conditions together produce observable CP-violation - (sinθ

_{13}sind

_{CP}) ≠0.

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