Type II seesaw mechanism, deviations from bimaximal neutrino mixing, and leptogenesis
- Scuola Internazionale Superiore di Studi Avanzati, Via Beirut 2-4, I-34014 Trieste (Italy)
A possible interplay of both terms in the type II seesaw formula is illustrated by presenting a novel way to generate deviations from exact bimaximal neutrino mixing. In the type II seesaw mechanism with dominance of the noncanonical SU(2){sub L} triplet term, the conventional seesaw term can naturally give a small contribution to the neutrino mass matrix. Nevertheless, if the triplet term corresponds to the bimaximal mixing scheme in the normal hierarchy, the small contribution of the conventional seesaw term naturally generates nonmaximal solar neutrino mixing. Atmospheric neutrino mixing is also reduced from maximal, corresponding to 1-sin{sup 2}2{theta}{sub 23} of order 0.01. Also, small but nonvanishing U{sub e3} of order 0.001 is obtained. It is also possible that the {delta}m{sup 2} responsible for solar neutrino oscillations is induced by the small conventional seesaw term. Larger deviations from zero U{sub e3} and from maximal atmospheric neutrino mixing are then expected. This scenario links the small ratio of the solar and atmospheric {delta}m{sup 2} with the deviation from maximal solar neutrino mixing. We comment on leptogenesis in this scenario and compare the contributions to the decay asymmetry of the heavy Majorana neutrinos as induced by themselves and by the triplet.
- OSTI ID:
- 20705317
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 70, Issue 7; Other Information: DOI: 10.1103/PhysRevD.70.073010; (c) 2004 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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