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arXiv · 2210.05307

Undemocratic Dirac seesaw

Su-Ping Chen·Pei-Hong Gu
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Abstract

The standard model left-handed neutrinos and several right-handed neutrinos can obtain a tiny Dirac mass matrix through their mixings with relatively heavy Dirac fermions. In this Dirac seesaw scenario, the mixings involving the left-handed neutrinos can be allowed much larger than those involving the right-handed neutrinos. This undemocratic parameter choice is attractive to phenomenology. We show that the small mixings between the heavy Dirac fermions and the right-handed neutrinos can have a common origin with the observed baryon asymmetry in the universe. We also connect the introduction of right-handed neutrinos to the existence and stability of dark matter by a new $U(1)$ gauge symmetry for dark photon or baryon-minus-lepton number. We then specify how to embed our scenario into a left-right symmetric theory or a grand unification theory.

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Su-Ping Chen, Pei-Hong Gu. 2022-10-11. Undemocratic Dirac seesaw. https://doi.org/10.1016/j.nuclphysb.2022.116028

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