In constant-roll inflation , the scalar field that drives the accelerated expansion of the Universe is rolling down its potential at a constant rate .
Within this framework , we highlight the relations between the Hubble slow-roll parameters and the potential ones , studying in detail the case of a single-field Coleman-Weinberg model characterised by a non-minimal coupling of the inflaton to gravity .
With respect to the exact constant-roll predictions , we find that assuming an approximate slow-roll behaviour yields a difference of \Delta r = 0.001 in the tensor-to-scalar ratio prediction .
Such a discrepancy is in principle testable by future satellite missions .
As for the scalar spectral index n _ { s } , we find that the existing 2- \sigma bound constrains the value of the non-minimal coupling to \xi _ { \phi } \sim 0.29 - 0.31 in the model under consideration .