Gravitational wave complementarity and impact of NANOGrav data on gravitational leptogenesis

In seesaw mechanism, if right handed (RH) neutrino masses are generated dynamically by a gauged U(1) symmetry breaking, a stochastic gravitational wave background (SGWB) sourced by a cosmic string network could be a potential probe of leptogenesis. We show that the leptogenesis mechanism that facilitates the dominant production of lepton asymmetry via the quantum effects of right-handed neutrinos in gravitational background, can be probed by GW detectors as well as next-generation neutrinoless double beta decay (0 nu beta beta) experiments in a complementary way. We infer that for a successful leptogenesis, an exclusion limit on f - Omega (GW)h(2) plane would correspond to an exclusion on the |m(beta beta)| - m(1) plane as well. We consider a normal light neutrino mass ordering and discuss how recent NANOGrav pulsar timing data (if interpreted as GW signal) e.g., at 95% CL, would correlate with the potential discovery or null signal in 0 nu beta beta decay experiments.

Automated summary

Studies have shown that the quantum effects of right-handed neutrinos in a gravitational background facilitate the leptogenesis mechanism, which can be probed complementarily by GW detectors and next-generation neutrinoless double beta decay experiments. Successful leptogenesis should correspond to specific plane limits, while recent pulsar timing data could be related to the results of 0νββ decay experiments.