Fractional attractors in light of the latest ACT observations

Understand

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 $V(\phi)$, the fractional attractors predict both a spectral index $n_s$ and a tensor-to-scalar ratio $r$ that fall within the $1\sigma$ region of the combined ACT+Planck data for a wide range of parameters.
• We also provide a numerical fit for the parameter space of this models in the case of a simple quadratic and quartic fractional potential.