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arXiv · 2006.01406

Gravitational waves from breaking of an extra $U(1)$ in $SO(10)$ grand unification

Nobuchika Okada·Osamu Seto·Hikaru Uchida
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Abstract

In a class of gauged $U(1)$ extended Standard Models (SMs), the breaking of the $U(1)$ symmetry is not only a source for Majorana masses of right-handed (RH) neutrinos crucial for the seesaw mechanism, but also a source of stochastic gravitational wave (GW) background. Such $U(1)$ extended models are well-motivated from the viewpoint of grand unification. In this paper, we discuss a successful ultraviolet completion of a $U(1)$ extended SM by an $SO(10)$ grand unified model through an intermediate step of $SU(5) \times U(1)$ unification. With a parameter set that is compatible with the $SO(10)$ grand unification, we find that a first-order phase transition associated with the $U(1)$ symmetry breaking can be strong enough to generate GWs with a detectable size of amplitude. We also find that the resultant GW amplitude reduces and its peak frequency becomes higher as the RH neutrino masses increase.

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Nobuchika Okada, Osamu Seto, Hikaru Uchida. 2020-06-02. Gravitational waves from breaking of an extra $U(1)$ in $SO(10)$ grand unification. https://doi.org/10.1093/ptep/ptab003

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