Generalized Brans–Dicke inflation with a quartic potential
Behzad Tahmasebzadeh (Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), P.O. Box 45195-1159, Zanjan, Iran); Kayoomars Karami (Department of Physics, University of Kurdistan, Pasdaran Street, P.O. Box 66177-15175, Sanandaj, Iran)
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.
