Curvaton in large field inflation

Abstract

We comprehensively explore the quadratic curvaton models in the chaotic inflation. In the light of the BICEP2 result $r \approx 0.2$, all model parameters and relevant observables are computed. It is found the curvaton field value is constrained into a narrow range, $\sigma_* = \mathcal{O}(10^{-2}$-$10^{-1})$ and the running of the spectral index is $n_s' \gtrsim -10^{-3}$. We show that if the curvaton is added, the models are heavily degenerated on the $n_s$ - $r$ plane. However, introducing a new plane, the degeneracy can be resolved. To distinguish the curvaton models, precise measurements of not only $r$ but also $n_s'$ and the tensor tilt $n_T$ are required.