Horizontal SU(2) symmetry revisited

Systematic study of fermion masses and mixing angles in horizontal SU(2) gauge theory

“…In such cases, a second χ Higgs multiplet may be added (see ref. [14]), having the effect of altering U KM to…”

“…Small deviations from this symmetry are possible, but the exact symmetry would be expected to show through at the tree level. One candidate model for such a symmetry is the [14], it provides tree level masses for the second and third generation, including neutrinos, but generates non-zero lepton mixing angles at tree level, which therefore may be quite large); the model L 3 + Q 4 + N 1 , with φ higgs (here, all the fermion masses and mixing angles would need to be generated from mixing with ν 2 through radiative corrections. This seems a little dubious, especially since one would expect the second generation particles to receive greater masses than the third generation.…”

“…Various symmetries have been investigated in the literature, both discrete [1][2][3] and continuous. Possible continuous symmetries to look at are U(1) [4][5][6], SU(2) [7][8][9][10][11][12][13][14][15] and SU(3) [16][17][18][19] symmetries. While there has been considerable work on SU(2) horizontal symmetry models, such investigations have been based on only a few possible sets of fermion and Higgs boson assignments.…”