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Normal vs. Inverted Hierarchy in Type I Seesaw Models

Carl H. Albright
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Abstract

We demonstrate that, for every grand unified model based on a conventional type I seesaw mechanism leading to a normal light neutrino mass hierarchy, one can easily generate a corresponding model with an inverted hierarchy which yields the same neutrino oscillation parameters. However, the latter type model has several unattractive instabilities which will disfavor any grand unified type I seesaw model, if an inverted neutrino mass hierarchy is observed experimentally. This should be contrasted with the softly-broken $L_e - L_μ- L_τ$ flavor symmetry models which are eliminated, if the data favors a normal mass hierarchy.

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Carl H. Albright. 2004-08-24. Normal vs. Inverted Hierarchy in Type I Seesaw Models. https://doi.org/10.1016/j.physletb.2004.08.050

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