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arXiv · 2110.14665

A $\nu$ scalar in the early universe and $(g-2)_{\mu}$

Jia Liu·Navin McGinnis·Carlos E. M. Wagner·Xiao-Ping Wang
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Abstract

We investigate a concrete scenario of a light scalar with a mass around 1 MeV which can be connected to the origin of neutrino masses and simultaneously survive current bounds on relativistic degrees of freedom in the early universe. In particular we show that a feeble coupling to the Standard Model neutrinos can relax the stringent bounds on the decays to photons inferred from the measured value of $N_{\rm eff}$. Interestingly, we find that such a scalar whose diphoton coupling is generated by a tree-level coupling to the muon of similar strength as that of the Standard Model Higgs boson can simultaneously explain the long-standing discrepancy in the measured value of the muon magnetic moment. We present a possible ultraviolet completion of this scenario providing a link between new physics in the early universe and the generation of neutrino masses.

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Jia Liu, Navin McGinnis, Carlos E. M. Wagner, Xiao-Ping Wang. 2021-10-27. A $\nu$ scalar in the early universe and $(g-2)_{\mu}$. https://doi.org/10.1103/physrevd.105.l051702

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