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arXiv · 1602.03003

Why three generations?

Masahiro Ibe·Alexander Kusenko·Tsutomu T. Yanagida
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Abstract

We discuss an anthropic explanation of why there exist three generations of fermions. If one assumes that the right-handed neutrino sector is responsible for both the matter-antimatter asymmetry and the dark matter, then anthropic selection favors three or more families of fermions. For successful leptogenesis, at least two right-handed neutrinos are needed, while the third right-handed neutrino is invoked to play the role of dark matter. The number of the right-handed neutrinos is tied to the number of generations by the anomaly constraints of the $U(1)_{B-L}$ gauge symmetry. Combining anthropic arguments with observational constraints, we obtain predictions for the $X$-ray observations, as well as for neutrinoless double-beta decay.

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Masahiro Ibe, Alexander Kusenko, Tsutomu T. Yanagida. 2016-02-09. Why three generations?. https://doi.org/10.1016/j.physletb.2016.05.025

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