A. Zee, Quantum Field Theory in a Nutshell · Problem VIII.3.2
Field Theory Redux
Physics — QFT
Problem
Assuming the nonexistence of the right handed neutrino field νR (i.e., assuming the minimal particle content of the standard model) write down all SU(2)⊗U(1) invariant terms that violate lepton number L by 2 and hence construct an effective field theory of the neutrino mass. Of course, by constructing a specific theory one can be much more predictive. Out of the product lLlL we can form a Lorentz scalar transforming as either a singlet or triplet under SU(2). Take the singlet case and construct a theory.