Missing Doublet Multiplet as the Origin of the Doublet-Triplet Splitting in SUSY SU(6)

Abstract

In a $SU(6)$ gauge theory we found the irreducible representation (175-plet) which does not contain the Higgs doublet. Using this representation we construct two SUSY $SU(6)$ models in which the doublet-triplet splitting occurs naturally, without fine tuning. The crucial role is played by the ``custodial" global $SU(2{)}_H$ in combination with discrete or continuous $R$ symmetries.

Comments: 11 pages, LaTex