We reconsider the original model of quadratic hybrid inflation in light of the WMAP three-year results and study the possibility of obtaining a spectral index of primordial density perturbations , n _ { s } , smaller than one from this model .
The original hybrid inflation model naturally predicts n _ { s } \geq 1 in the false vacuum dominated regime but it is also possible to have n _ { s } < 1 when the quadratic term dominates .
We therefore investigate whether there is also an intermediate regime compatible with the latest constraints , where the scalar field value during the last 50 e-folds of inflation is less than the Planck scale .