Solving the Flavour Problem in Supersymmetric Standard Models with Three Higgs Families

R. Howl, S. F. King

Published 2009-08-14, updated 2010-03-17Version 3

We show how a non-Abelian family symmetry Delta(27) can be used to solve the flavour problem of supersymmetric standard models containing three Higgs families such as the Exceptional Supersymmetric Standard Model (E(6)SSM). The three 27 dimensional families of the E(6)SSM, including the three families of Higgs fields, transform in a triplet representation of the Delta(27) family symmetry, allowing the family symmetry to commute with a possible high energy E(6) symmetry. The Delta(27) family symmetry here provides a high energy understanding of the Z(2)H symmetry of the E(6)SSM, which solves the flavour changing neutral current problem of the three families of Higgs fields. The main phenomenological predictions of the model are tri-bi-maximal mixing for leptons, two almost degenerate LSPs and two almost degenerate families of colour triplet D-fermions, providing a clear prediction for the LHC. In addition the model predicts PGBs with masses below the TeV scale, and possibly much lighter, which appears to be a quite general and robust prediction of all models based on the D-term vacuum alignment mechanism.