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 2.4 \times 10 ^ { -14 } \lesssim \kappa \lesssim 5.7 \times 10 ^ { -14 } , 0.931 \lesssim n _ { s } \lesssim 0.958 and 0.038 \lesssim r \lesssim 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 \lesssim 7.7 \times 10 ^ { -15 } , 0.929 \lesssim n _ { s } \lesssim 0.966 and 0.023 \lesssim r \lesssim 0.135 .
The next round of precision experiments should provide a more stringent test of realistic chaotic \phi ^ { 2 } and \phi ^ { 4 } inflation .