On expansions in neutrino effective field theory

Understand

We match the seesaw model for generating neutrino masses onto the Standard Model Effective Field Theory (SMEFT).

• We perform this matching at tree level up to dimension seven in the operator expansion.
• We explain how some of the perturbations of the neutrino mass matrix due to operators of mass dimension greater than five are tied to integrating out the heavy Majorana mass eigenstates in sequence.
• We demonstrate that the low energy limit of seesaw models are well described by the SMEFT, particularly when constructed using a flavour space expansion.