Within the supersymmetric SO(10) GUT we explore the possibility of the light
Higgs doublet being a member of the 16-dimensional spinorial representation.
This fact is ultimately related with the assumption that the light matter (at
least partially) resides in some of the tensor representations as well. Several
interesting features emerge. First, provided that the same 16-plet is
responsible for the breaking SO(10)→SU(5), the heaviness of the
top can automatically follow from the field content at MGUT, without need
of any flavour symmetries. Secondly, the doublet--triplet splitting problem
receives a new natural solution. In addition, a dimension=5 (Higgsino mediated)
proton decay can be naturally suppressed. We construct explicit SO(10) models
with the above properties, with most general superpotentials under the
symmetries.Comment: 13 pages, Late
