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arXiv · 2202.10250

Effective neutrino number shift from keV-vacuum neutrinophilic 2HDM

Shao-Ping Li·Xin-Qiang Li·Xin-Shuai Yan·Ya-Dong Yang
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Abstract

If the Dirac neutrino masses are generated by a new scalar doublet with a vacuum at keV order, there would be rare hope to probe the framework in low-energy flavor physics, such as the lepton-flavor violating processes. However, the predicted neutrino Yukawa couplings being around the order of electronic Yukawa can realize a purely thermal Dirac leptogenesis, and thus render a more direct link between the high- and the low-energy CP violation. Despite its inert property in the low-energy flavor processes, the keV-vacuum induced Dirac neutrino model can generate a significant shift of the effective neutrino number, which can in turn be probed by the big-bang nucleosynthesis and cosmic microwave background epochs. We show that such a keV-vacuum induced Dirac neutrino model is already constrained by the current observations and will be probed with forecast sensitivity, serving therefore as a complementary avenue to test the Dirac leptogenesis.

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Shao-Ping Li, Xin-Qiang Li, Xin-Shuai Yan, Ya-Dong Yang. 2022-02-21. Effective neutrino number shift from keV-vacuum neutrinophilic 2HDM. https://doi.org/10.1088/1674-1137/acb6de

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