Implications of new generations on neutrino masses

Understand

We explore the possible implications that new families, that are being searched for at the LHC, would have on neutrino masses.

• In particular, we have explored the possibility that the smallness of the observed neutrino masses is naturally understood in a modified version of the Standard Model (SM) with complete extra generations of fermions, i.e., that have right-handed neutrinos, in which neutrino masses are generated at two loops.
• With one extra family it is not possible to fit the observed spectrum of masses and mixings.
• However, the radiative mass generated provides an important constraint in these kind of models, so the neutrino masses do not exceed their cosmological bound.