SUGRA Hybrid Inflation with Shift Symmetry
  We propose a solution to the eta-problem in supergravity (SUGRA) hybrid
inflation using a Nambu-Goldstone-like shift symmetry within a new class of
models. The flatness of the tree-level inflaton potential is ensured by shift
symmetry invariance of the Kaehler potential, while a small symmetry breaking
term in the superpotential gives rise to a slope of the potential at
loop-level. In the proposed class of inflation models, potentially dangerous
couplings between the inflaton and the moduli sector are avoided. We also
discuss under which conditions the predicted spectral index can be in agreement
with the best-fit-value of the latest WMAP observation n_s ~ 0.96,
corresponding to a hilltop-type inflaton potential at loop-level.
