Generalized Brans-Dicke inflation with a quartic potential

Within the framework of Brans-Dicke gravity, we investigate inflation with the quartic potential, λφ4/4, in the presence of generalized Brans-Dicke parameter ωGBD(φ). We obtain the inflationary observables containing the scalar spectral index, the tensor-to-scalar ratio, the running of the scalar spectral index and the equilateral non-Gaussianity parameter in terms of general form of the potential U(φ) and ωGBD(φ). For the quartic potential, our results show that the predictions of the model are in well agreement with the Planck 2015 data for the generalized Brans-Dicke parameters ωGBD(φ)=ω0φn and ω0ebφ. This is in contrast with both the Einstein and standard Brans-Dicke gravity, in which the result of quartic potential is disfavored by the Planck data.