Relatore
Dr.
Antonio Racioppi
Descrizione
Palatini $F(R)$ gravity proved to be powerful tool in order to realize asymptotically flat inflaton potentials. Unfortunately it also inevitably implies higher-order inflaton kinetic terms in the Einstein frame that might jeopardize the evolution of the system out of the slow-roll regime. We prove that a $F(R-X)$ gravity, where $X$ is the inflaton kinetic term, solves the issue. Moreover, when $F$ is a quadratic (or higher order) function such a choice easily leads to a new class of inflationary attractors, fractional attractors, that generalizes the already well-known polynomial $\alpha$-attractors.
