Prospects of gravitational waves in the minimal left-right symmetric model

The left-right symmetric model (LRSM) is a well-motivated framework to restore parity and implement seesaw mechanisms for the tiny neutrino masses at or above the TeV-scale, and has a very rich phenomenology at both the high-energy and high-precision frontiers. In this paper we examine the phase transition and resultant gravitational waves (GWs) in the minimal version of LRSM. Taking into account all the theoretical and experimental constraints on LRSM, we identify the parameter regions with strong first-order phase transition and detectable GWs in the future experiments. It turns out in a sizeable region of the parameter space, GWs can be generated in the phase transition with the strength of 10(-17) to 10(-12) at the frequency of 0.1 to 10 Hz, which can be detected by BBO and DECIGO. Furthermore, GWs in the LRSM favor a relatively light SU(2)(R)-breaking scalar H30, which is largely complementary to the direct searches of a long-lived neutral scalar at the high-energy colliders. It is found that the other heavy scalars and the right-handed neutrinos in the LRSM also play an important part for GW signal production in the phase transition.

Automated summary

The left-right symmetric model is a well-motivated framework for restoring parity and implementing seesaw mechanisms for tiny neutrino masses. This paper examines the phase transition and gravitational waves in the minimal version of LRSM, identifying parameter regions with strong first-order phase transition and detectable GWs. It is found that in a substantial region of the parameter space, GWs can be generated in the phase transition and favor a relatively light SU(2)(R)-breaking scalar H30, which complements direct searches at high-energy colliders.