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We consider a variant of hybrid inflation where the waterfall phase transition
happens during inflation. By tuning the parameters associated with the mass of
the waterfall field, we arrange that the phase transition is not sharp so
inflation can proceed for an extended period after the waterfall phase
transition. We show that one can work in the limit where the quantum
back-reactions are subdominant compared to the classical back-reactions. It
is shown that significant amount of large scale curvature perturbations are
induced from the entropy perturbations. The spectral index of the curvature
perturbations changes from blue to red tilt which can have interesting
observational consequences on CMB. The non-Gausian parameter $f_{NL}$ is
calculated to be $\lesssim 1$ but much bigger than the slow-roll parameters.
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