We briefly summarize and update a class of inflationary models from the early eighties based on a quartic ( Coleman-Weinberg ) potential for a gauge singlet scalar ( inflaton ) field . For vacuum energy scales comparable to the grand unification scale , the scalar spectral index n _ { s } \simeq 0.94 – 0.97 , in very good agreement with the WMAP three year results . The tensor to scalar ratio r \lesssim 0.14 while \alpha \equiv { d } n _ { s } / { d } \ln k is \simeq - 10 ^ { -3 } . An SO ( 10 ) version naturally explains the observed baryon asymmetry via non-thermal leptogenesis .