Parameterizing Majorana Neutrino Couplings in the Higgs Sector

Understand

Nonzero masses for the active neutrinos - regardless of their nature or origin - arise only after electroweak symmetry breaking.

• We discuss the parameterization of neutrino couplings to a Higgs sector consisting of one SU(2)_L scalar doublet and one SU(2)_L scalar triplet, and allow for right-handed neutrinos whose Majorana mass parameters arise from the vacuum expectation value of a Standard Model scalar singlet.
• If the neutrinos are Majorana fermions, all Yukawa couplings can be expressed as functions of the neutrino mass eigenvalues and a subset of the elements of the neutrino mixing matrix.
• In the mass basis, the Yukawa couplings are, in general, not diagonal.