Savior Curvatons and Large non-Gaussianity

Understand

Curvatons are light (compared to the Hubble scale during inflation) spectator fields during inflation that potentially contribute to adiabatic curvature perturbations post-inflation.

• They can alter CMB observables such as the spectral index $n_s$, the tensor-to-scalar ratio $r$, and the local non-Gaussianity $\;f_{\rm NL}^{\rm (loc)}$.
• We systematically explore the observable space of a curvaton with a quadratic potential.
• We find that when the underlying inflation model does not satisfy the $n_s$ and $r$ observational constraints but can be made viable with a significant contribution from what we call a savior curvaton, a large $\;f_{\rm NL}^{\rm (loc)}$ is inevitable.