  It is well known that the non-minimal coupling $\xi\phi^2R$ between the
inflaton and the Ricci scalar affects predictions of single field inflation
models. In particular, the $\lambda\phi^4$ quartic inflation potential with
$\xi\gtrsim0.005$ is one of the simplest models that agree with the current
data. After reviewing the inflationary predictions of this potential, we
analyze the effects of the radiative corrections due to couplings of the
inflaton to other scalar fields or fermions. Using two different prescriptions
discussed in the literature, we calculate the range of these coupling parameter
values for which the spectral index $n_s$ and the tensor-to-scalar ratio $r$
are in agreement with the data taken by the Keck Array/BICEP2 and Planck
collaborations.
