Inflationary observables in $F(R)$ gravity

Abstract

We present phenomenological signatures for a modified gravity model f(R), constructed with linear, quadratic, cubic and quartic terms. The obtained signatures satisfy current phenomenological bounds reported by PLANCK and BICEP3. Furthermore, two of the model solutions $\sigma_1$ and $\sigma_2$ seem to favor a much lower value for the tensor-to-scalar ratio $0.0005<r_{\sigma_1}<0.0015$ and $r_{\sigma_2}<0.00015$ than the current reported experimental bounds. The results we obtained are quantitatively similar to those presented in previous studies for $R^3$ models.