Speaker
Description
Lepton number violating (LNV) interactions occur in the Standard Model Effective Field Theory (SMEFT) at odd dimensions starting from the dimension-5 Weinberg operator. The operators higher than dimension-5 are suppressed by additional powers of the heavy new scale. However, they can be crucial when traditional seesaw mechanisms leading to tree-level dimension-5 contributions are absent. Considering the example of minimal tree-level UV-completions for dimension-7 SMEFT LNV operators, I will discuss how a dimensional-regularisation-based approach can provide a more accurate estimate for the radiative neutrino masses when the new physics fields are hierarchical in mass, as compared to the cut-off-regularisation-based approach often employed in the literature. This opens up new viable regions of parameter space close to the current limits set by searches for neutrinoless double beta decay and the LHC that would previously have been thought to be excluded by neutrino-mass constraints.
