Particle and Gravitational Wave Probes of Minimal Seesaw Neutrinos

Abstract

Observable gravitational waves (GWs) from first-order phase transitions (FOPTs) can coexist with distinct particle physics signatures. These include same-sign dilepton plus four~jet events at colliders, such as $e^{+}{e}^{-}/{\mu }^{+}{\mu }^{-}\to {\ell }^{\pm }{\ell }^{\pm }4j$, neutrinoless double beta decay, as well as charged lepton flavor violating (cLFV) processes such as $\mu \to e\gamma$. We explore this synergy within the minimal low-scale linear seesaw model. This framework successfully reproduces neutrino oscillation data, providing a direct avenue to probe the neutrino mass ordering and Majorana nature at colliders. Crucially, the FOPT responsible for the GW background is driven by a leptophilic Higgs doublet, establishing a direct link between early-universe cosmology and terrestrial laboratory experiments.

Comments: 23 pages, 9 figures, 1 Table