Fractional attractors in light of the latest ACT observations

Abstract

In light of the latest results from ACT observations we review a class of potentials labeled as fractional attractors, that can originate from Palatini gravity. We show that, for certain choices of the scalar potential $V\left(\varphi \right)$, the fractional attractors predict both a spectral index $n_s$ and a tensor-to-scalar ratio r that fall within the 1σ region of the combined ACT+Planck data for a wide range of parameters. We also provide a numerical fit for the parameter space of these models in the case of a simple quadratic and quartic fractional potential.