Abstract
We analyze a class of supersymmetric models first introduced by Arkani-Hamed et al. and Borzumati et al. in which the light neutrino masses result from higher-dimensional supersymmetry-breaking terms in the MSSM super-potentials and Kahler potentials. The mechanism is closely related to the Giudice–Masiero mechanism for the MSSM μ parameter, and leads to TeV-scale right-handed neutrino and sneutrino states, that are in principle accessible to direct experimental study. The dominant contribution to the light neutrino (Majorana) mass matrix is a one-loop term induced by a lepton-number violating B-term for the sneutrino states that is naturally present. We focus upon the simplification and analysis of the flavour structure of this general class of models, finding that simple and novel origins for the light neutrino mass matrix are possible. We find that a subdominant tree-level ‘see-saw’ contribution may lead to interesting perturbations of the leading one-loop-induced flavour structure, possibly generating the small ratio Δmsolar2/Δmatm2 dynamically.
Highlights
The case for the existence of small neutrino masses and associated physical neutrino mixing angles has enormously strengthened in recent years as a consequence of the numerous experimental studies of atmospheric and solar neutrinos, and neutrinos from terrestrial sources
In overall structure our models are similar to those previously studied in Refs.[7, 8, 9, 10], in that the dominant contribution to the light neutrino masses arises from a one-loop diagram involving a supersymmetry breaking and lepton-number violating B-term for the right handed sneutrinos, but, by an alteration of the model, we have been able to significantly simplify the way in which the flavour structure of the light neutrino mass matrix arises, and are able for the first time to study in detail some of the consequences of this very attractive class of models
The mechanism is closely related to the Giudice-Masiero mechanism for the minimal supersymmetric standard model (MSSM) Higgs μ parameter, and in particular leads to TeV-scale rhd neutrino and sneutrino states, that are in principle accessible to direct experimental study, unlike traditional see-saw mechanisms
Summary
The case for the existence of small neutrino masses and associated physical neutrino mixing angles has enormously strengthened in recent years as a consequence of the numerous experimental studies of atmospheric and solar neutrinos, and neutrinos from terrestrial sources. In particular there is a tension between the strongly hierarchical nature of the observed Yukawa couplings in the quark and charged lepton sectors, and the essentially hierarchy-free masses implied by the ∆m2’s Both the θ12 and θ23 mixing angles are large while the angle θ13 is small which is in sharp contrast with the corresponding mixings in the quark sector which are all small. These problems can be solved in specific models, for example the ∆m2 values can be fitted by taking the spectrum of rhd neutrino masses to be hierarchical in such a way as to almost compensate for the hierarchical neutrino Yukawa couplings. In overall structure our models are similar to those previously studied in Refs.[7, 8, 9, 10], in that the dominant contribution to the light neutrino masses arises from a one-loop diagram involving a supersymmetry breaking and lepton-number violating B-term for the right handed sneutrinos, but, by an alteration of the model, we have been able to significantly simplify the way in which the flavour structure of the light neutrino mass matrix arises, and are able for the first time to study in detail some of the consequences of this very attractive class of models
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