Paper detail

Exotic properties of neutrinos using effective Lagrangians and specific models

This doctoral dissertation presents several works on nonstandard properties of neutrinos exploiting the synergies between effective field theory and models. The phenomena are first analysed by means of effective operators, which allow to discuss their phenomenological consequences and to derive estimations about the mass scale of the heavy particles needed to induce the new interactions. In a second phase we propose models that realise the effective operators, allowing us to check the conclusions of effective field theory as well as to extract new phenomenological features of the scenarios considered. The text is divided into two parts: in the first one we apply these ideas to an effective interaction that generates magnetic dipole moments for right-handed neutrinos, and in the second one we discuss a family of operators that violate lepton number without quarks, and which can allow for large rates of neutrinoless double $β$ decay and small neutrino masses. The right-handed neutrino magnetic moments have the potential to show up in many different scenarios, and the nonobservation of the associated phenomenology allows to constrain their value, and therefore the associated new physics scale. The operators discussed in the second part of the text can potentially dominate neutrinoless double $β$ decay and provide signals in the next generation of experiments; they can be classified according to the chirality of the two final-state leptons, and induce neutrino mass matrices with a well-defined hierarchy related to that of the charged lepton masses. In both cases we provide example models that realise the phenomenology and we discuss their observability in ongoing and near-future experiments.