We generalize the scalar-curvature coupling model { \xi \Phi ^ { 2 } R } of Higgs inflation to { \xi \Phi ^ { a } R ^ { b } } to study inflation .
We compute the amplitude and spectral index of curvature perturbations generated during inflation and fix the parameters of the model by comparing these with the Planck + WP data .
We find that if the scalar self coupling \lambda is in the range ( 10 ^ { -5 } -0.1 ) , parameter a in the range ( 2.3 - 3.6 ) and b in the range ( 0.77 - 0.22 ) at the Planck scale , one can have a viable inflation model even for \xi \simeq 1 .
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 \frac { \lambda } { 4 } \Phi ^ { 4 } 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 \xi \Phi ^ { 2 } R Higgs inflation models .
We conclude that the Higgs field may still be a good candidate for being the inflaton in the early universe if one considers higher dimensional curvature coupling .

Keywords : Higgs Inflation ; CMB spectrum ; Non-minimal coupling ; Jordan frame ; Einstein frame ; Perturbations .