  We investigate the parameter spaces of hybrid inflation model with special
attention paid to the dynamics of waterfall field and curvature perturbations
induced from its quantum fluctuations. Depending on the inflaton field value at
the time of phase transition and the sharpness of the phase transition
inflation can have multiple extended stages. We find that for models with mild
phase transition the induced curvature perturbation from the waterfall field is
too large to satisfy the COBE normalization. We investigate the model parameter
space where the curvature perturbations from the waterfall quantum fluctuations
vary between the results of standard hybrid inflation and the results obtained
here.
