In cosmic inflation driven by a scalar gauge singlet field with a tree level Higgs potential , the scalar to tensor ratio r is estimated to be larger than 0.036 , provided the scalar spectral index n _ { s } \geq 0.96 .
We discuss quantum smearing of these predictions arising from the inflaton couplings to other particles such as GUT scalars , and show that these corrections can significantly decrease r .
However , for n _ { s } \geq 0.96 , we obtain r \geq 0.02 which can be tested by the Planck satellite .