A simple $$F(\mathcal{R},\phi )$$ deformation of Starobinsky inflationary model

Abstract

We study a model including a real scalar field $$\phi $$ϕ non-minimally coupled to $$F(\mathcal{R})$$F(R) gravity, which is conformally equivalent to an Einstein–Hilbert theory, involving two real scalar fields. We consider three special cases of the potential of the field $$\phi $$ϕ in the $$F(\mathcal{R})$$F(R)-frame: a vanishing potential, a mass term and a Higgs potential. All these lead to non-trivial two-field potentials in the Einstein-frame which in particular directions resemble the well-known Starobinsky model. We find, that all these cases can yield viable inflationary models in complete agreement with current observational data.

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