Relaxing inflation models with nonminimal coupling: A general study

We investigate the predictions of inflation models with a nonminimal coupling to gravity for inflationary observables such as the spectral index and tensor-to-scalar ratio in a general setting. We argue that, depending on the relation between the Jordan frame potential and a function characterizing the nonminimal coupling, one can classify the model into three categories, each of which gives distinctive predictions for the inflationary observables. We derive general predictions for each class and also investigate some explicit models to discuss how the general features arise. Our results would be useful to design an inflation model consistent with observational constraints with a nonminimal coupling to gravity.

Automated summary

In this study, we investigate the predictions of inflation models with a nonminimal coupling to gravity for inflationary observables such as the spectral index and tensor-to-scalar ratio in a general setting. Depending on the relation between the Jordan frame potential and a function characterizing the nonminimal coupling, the models can be classified into three categories, each giving distinctive predictions for the inflationary observables. We derive general predictions for each class and investigate some specific models to understand the underlying features.