Subcritical hybrid inflation in a generalized superconformal model

We study a generalized superconformal model that gives rise to a subcritical regime of D-term hybrid inflation. Exhibiting the model both in a Jordan frame and in the Einstein frame, the effective potential of the subcritical regime is derived in the Einstein frame. It turns out that the inflaton-waterfall field dynamics leads to various types of inflaton potential. Consequently, the tensor-to-scalar ratio is found to range from 10(-4) (10(-3)) to 0.1 for getting 60 (50) e-folds before the end of inflation.