TY - JOUR

T1 - Parametrizing Majorana neutrino couplings in the Higgs sector

AU - De Gouvêa, André

AU - Huang, Wei Chih

AU - Shalgar, Shashank

N1 - Copyright:
Copyright 2011 Elsevier B.V., All rights reserved.

PY - 2011/8/11

Y1 - 2011/8/11

N2 - 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. This is to be contrasted to the case of charged fermions or Dirac neutrinos, where couplings to the Higgs-boson are diagonal in the mass basis and proportional only to the fermion masses. Nonetheless, all physically distinguishable parameters can be reached if all neutrino masses are constrained to be positive, all mixing angles constrained to lie in the first quadrant (θ[0,π/2]), and all Majorana phases to lie in the first two quadrants (φ[0,π}), as long as all Dirac phases vary within the entire unit circle (δ[0,2π}). We discuss several concrete examples and comment on the Casas-Ibarra parameterization for the neutrino Yukawa couplings in the case of the type I seesaw Lagrangian. We also comment on the case where SU(2) L fermion triplets replace the right-handed neutrinos.

AB - 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. This is to be contrasted to the case of charged fermions or Dirac neutrinos, where couplings to the Higgs-boson are diagonal in the mass basis and proportional only to the fermion masses. Nonetheless, all physically distinguishable parameters can be reached if all neutrino masses are constrained to be positive, all mixing angles constrained to lie in the first quadrant (θ[0,π/2]), and all Majorana phases to lie in the first two quadrants (φ[0,π}), as long as all Dirac phases vary within the entire unit circle (δ[0,2π}). We discuss several concrete examples and comment on the Casas-Ibarra parameterization for the neutrino Yukawa couplings in the case of the type I seesaw Lagrangian. We also comment on the case where SU(2) L fermion triplets replace the right-handed neutrinos.

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U2 - 10.1103/PhysRevD.84.035011

DO - 10.1103/PhysRevD.84.035011

M3 - Article

AN - SCOPUS:80052645098

VL - 84

JO - Physical Review D - Particles, Fields, Gravitation and Cosmology

JF - Physical Review D - Particles, Fields, Gravitation and Cosmology

SN - 1550-7998

IS - 3

M1 - 035011

ER -