Naturally small neutrino mass with asymptotic safety and gravitational-wave signatures

I will discuss a dynamical mechanism to generate small neutrino masses, based on a UV completion through asymptotically safe gravity, in the standard model with right-handed neutrinos and in the B-L model. A small Dirac mass for the neutrinos appears more naturally in the  B-L model compared to the standard model, when we account for quantum gravity corrections based on existing calculations. This mechanism can also accommodate Majorana neutrinos and pseudo-Dirac neutrinos, for various values of see-saw scale. I will discuss whether gravitational waves from first-order phase transition can distinguish these cases. In the presence of quantum scale invariance of the scalar potential — which is at odds with existing calculations in asymptotically safe quantum gravity — we find no gravitational wave signals. Forgoing this symmetry, we find an observable signal in new-generation space interferometers. However, its discriminating features are washed out by the strong dependence of the gravitational-wave spectrum on the mass parameter of the scalar potential.