Slow-roll approximations for Gauss-Bonnet inflation revisited

In our paper we consider the validity of slow-roll approximations for Gauss-Bonnet inflation introduced in [1]. In contrast to the cited paper where the coupling function before the Gauss-Bonnet term have been chosen as a decaying function of the scalar field, here we consider growing coupling functions. We have found that while in [1] new slow-roll approximations work considerably better, now they do not increase the precision. Moreover, we identify some cases where more involved approximations work worse than the standard one. Corresponding explanations of such a situation are given.

💡 Research Summary

The paper revisits the validity of slow‑roll approximations in Gauss‑Bonnet (GB) inflation, focusing on the class of models where the GB coupling function grows with the inflaton field, in contrast to the decreasing coupling studied in the earlier work