Speaker
Description
If Majorana neutrino masses are not generated via the dimension 5 Weinberg operator, the next simplest solution would be to generate them at dimension 7. We present a comprehensive analysis of dimension 7 lepton number violating (LNV) SMEFT operators and their phenomenological consequences for a range of experimental searches. Comparing low-scale observables such as flavour violating rare decays and neutrinoless double beta decay with collider searches as well as neutrino mass constraints, we show limits on each of the different $\Delta L = 2$ SMEFT operators at dimension 7. Furthermore, we systematically consider all possible tree-level UV-completions of these operators in a covariant derivative expansion framework, leading to the identification of the most phenomenologically promising New Physics scenarios as well as capturing the effect of a hierarchy in the internal heavy degrees of freedom.
