  We employ chaotic (phi^2 and phi^4) inflation to illustrate the important
role radiative corrections can play during the inflationary phase. Yukawa
interactions of phi, in particular, lead to corrections of the form -kappa
phi^4 ln(phi/mu), where kappa>0 and mu is a renormalization scale. For
instance, phi^4 chaotic inflation with radiative corrections looks compatible
with the most recent WMAP (5 year) analysis, in sharp contrast to the tree
level case. We obtain the 95% confidence limits 2.4x10^-14<~kappa<~5.7x10^-14,
0.931<~n_s<~0.958 and 0.038<~r<~0.205, where n_s and r respectively denote the
scalar spectral index and scalar to tensor ratio. The limits for phi^2
inflation are kappa<~7.7x10^-15, 0.929<~n_s<~0.966 and 0.023<~r<~0.135. The
next round of precision experiments should provide a more stringent test of
realistic chaotic phi^2 and phi^4 inflation.
