Probing low scale leptogenesis through gravitational wave

The quest for a common origin of neutrino mass and baryogenesis is one of the long-standing goals in particle physics. A minimal gauge extension of the Standard Model by U ( 1 ) B − L symmetry provides a unique scenario to explain the tiny mass of neutrinos as well as the observed baryon asymmetry, both by virtue of three right-handed neutrinos (RHNs). Additionally, the U ( 1 ) B − L breaking scalar that generates mass of the RHNs can produce a stochastic gravitational wave background (SGWB) via cosmological first-order phase transition. In this work, we systematically investigate TeV-scale leptogenesis considering flavor effects that are crucial in the low-temperature regime. We also explore all possible RHN production channels, which can have significant impact on the abundance of RHNs, depending on the value of the U ( 1 ) B − L gauge coupling. We demonstrate that the strong dependence of the U ( 1 ) B − L gauge sector on the baryon asymmetry as well as SGWB production can be utilized to probe a region of the model parameter space. In particular, we find that a U ( 1 ) B − L gauge boson with mass ∼ 10 TeV and gauge coupling ∼ 0.1 can explain the observed baryon asymmetry and produces a detectable SGWB in future detectors as well. Importantly, this region falls beyond the reach of the current collider sensitivity.