Non-trivial extension of Starobinsky inflation

We consider a non-canonic field in the context of Starobinsky inflation. work Einstein-frame. In this frame, gravitational part action is equivalent to Hilbert–Einstein action, plus scalar called scalaron. investigate model with heavy scalaron trapped at effective potential minimum, where its fluctuations are negligible. To be more explicit, we Dirac–Born–Infeld (DBI) field, which usually considered within brane inflation context, as field. Although, DBI governs through implicit dependence on Scalaron boost factor, and other quantities different from standard model. For appropriate parameters, consistent Planck results.