On the initial conditions for inflation with plateau potentials: the R plus R2 (super)gravity case

We discuss the initial conditions problem for inflation driven by the vacuum energy of a plateau potential, and in particular the Starobinsky inflation. We show that the supergravity embedding of the R + R-2 theory naturally decreases the size of the acausal homogeneity, required for the low-scale inflation to occur, thanks to the presence of the dynamical pure supergravitational "auxiliary" fields. We examine the evolution of the R R2 fields within a FLRW Universe. We also find a dependence of the initial conditions problem on the background spatial curvature.