Higgs Inflation in f (Փ, R)

The non minimal scalar-curvature coupling model  Փ2R  is one of the popular models which describes all the  phenomenons of inflation.The model also predict the Higgs field as a source of inflation with large value of coupling. In this talk, the  generalization of the scalar-curvature coupling model  Փ2 R of Higgs inflation to Փa Rb will be discussed. With proper choice of parameters of theory, one can have a viable inflation model even for coupling constant is order of unity. The tensor to scalar ratio r in this model is small and our model with scalar-curvature couplings is not ruled out by observational limits on r unlike the pure Փ4 theory. By requiring the curvature coupling parameter to be of order unity, we have evaded the problem of unitarity violation in scalar-graviton scatterings which plague the Փ2R Higgs inflation models.  Higgs field may still be a good candidate for being the inflaton in the early universe if one considers higher dimensional curvature coupling.