Palatini inflationary (non-)attractors: Universal mapping of observables

We study single-field slow-roll inflation in the context of Palatini gravity for the class of non-minimally coupled ξ-attractors, i.e., models where the same function f(ϕ) fixes both the non-minimal coupling, 1+ξf(ϕ), and the inflationary potential, V(ϕ) = V 0 f(ϕ) squared. As is well-known, for an arbitrary f(ϕ), the number of e-folds is, at leading order, independent of ξ. Thanks to this, we provide an immediate mapping between the observables of the non-minimally coupled setup and those of the minimally coupled one. In the strong coupling limit, the tensor-to-scalar ratio is, as usual, suppressed, while the scalar spectral index is shifted towards larger values, with the magnitude of the shift depending only on the tensor-to-scalar ratio associated with the original potential V(ϕ).