Reducing the spectral index in supernatural inflation

Supernatural inflation is an attractive model based on just a flat direction with soft supersymmetry breaking mass terms in the framework of supersymmetry. The beauty of the model is that it needs no fine-tuning. However, the prediction of the spectral index is n(s)greater than or similar to 1, in contrast to experimental data. In this paper, we discuss supernatural inflation with the spectral index reduced to n(s)=0.96 without any fine-tuning, considering the general feature that a flat direction is lifted by a nonrenormalizable term with an A-term.