Gauge Non-Singlet Inflation in SUSY GUTs
  We explore the novel possibility that the inflaton responsible for
cosmological inflation is a gauge non-singlet in supersymmetric (SUSY) Grand
Unified Theories (GUTs). For definiteness we consider SUSY hybrid inflation
where we show that the scalar components of gauge non-singlet superfields,
together with fields in conjugate representations, may form a D-flat direction
suitable for inflation. We apply these ideas to SUSY models with an Abelian
gauge group, a Pati-Salam gauge group and finally Grand Unified Theories based
on SO(10) where the scalar components of the matter superfields in the
$\sixteen$s may combine with a single $\bar {sixteen}$ to form the inflaton,
with the right-handed sneutrino direction providing a possible viable
trajectory for inflation. Assuming sneutrino inflation, we calculate the
one-loop Coleman-Weinberg corrections and the two-loop corrections from gauge
interactions giving rise to the "gauge \eta-problem" and show that both
corrections do not spoil inflation, and the monopole problem can be resolved.
The usual \eta-problem arising from supergravity may also be resolved using a
Heisenberg symmetry.
