Inflation due to non-minimal coupling of <i>f</i>(<i>R</i>) gravity to a scalar field

Abstract

In this work we investigate a inflationary scenario generated by a large scalar field ϕ that non-minimally couples to a f(R) modified gravity model. For a Starobinsky's like model, it is found that along a particular flat direction, the scalar potential takes a simple form where α(ϕ) is a non-minimal coupling to Ricci scalar R in the model. The inflation, therefore, is effectively represented as a single field inflaton scenario. For a specific example, such as a scalar potential V(ϕ) = μ1ι2 + μ2ϕ4, we found that the predictions match nicely in the 1σ confidence level of Plank TT, TE, EE+lowP combination data of Planck 2015 CMB data for 0 < μ3 ≤ 100, where . For example, taking μ3 = 0.01 the scalar-to-tensor ratio r = 0.0004 and and spectral index ns = 0.96985 for N* = 50 while taking μ3 = 100.0 produces r = 0.03 and ns = 0.96359 for N* = 60.