Is U(1) H a good family symmetry?

Abstract

ABSTRACT: We analyze U(1)H as a horizontal symmetry and its possibilities to explain the known elementary-fermion masses. We find that only two candidates, in the context of SU(3)c ⊗ SU(2)L ⊗ U(1)Y ⊗ U(1)H nonsuper-symmetric, are able to fit the experimental result mb«mt. identity, but it is a common prejudice to assume that the appropriate family symmetry may explain this fact as a consequence of (i) and (ii). In what follows we will enlarge the SM gauge group with an extra U(1)H horizontal local gauge symmetry (the simplest multi-family continuous symmetry we can think of). We then show that the structure SU(3)c ⊗ SU(2)L ⊗ U(1)Y ⊗ U(1)H by itself is able to explain (ii), and that the simplest supersymmetric (SUSY) extension of this model without a μ-term can not cope with (ii).

RESUMEN: las dos últimas páginas se encuentran en Springer y corresponden a las referencias.