Testing Seesaw and Leptogenesis with Gravitational Waves

Understand

We present the possibility that the seesaw mechanism with thermal leptogenesis can be tested using the stochastic gravitational background.

• Achieving neutrino masses consistent with atmospheric and solar neutrino data, while avoiding non-perturbative couplings, requires right-neutrinos lighter than the typical scale of grand unification.
• This scale separation suggests a symmetry protecting the right handed neutrinos from getting a mass.
• Thermal leptogenesis would then require that such a symmetry be broken below the reheating temperature.