Non-Gaussianity and gravitational wave background in curvaton with a double well potential

We study the density perturbation by a curvaton with a double well potential and give analytical expressions for the observables such as nonlinear parameters f(NL), g(NL) and tensor-to-scalar ratio r(T) with emphasizing the differences from the simple quadratic potential. We show that the level of non-Gaussianity and the tensor-to-scalar ratio depends crucially on the reheating temperature as well as the curvaton self-coupling constant for a given initial amplitude of the curvaton. We find that for a large initial field the nonlinear parameters f(NL) can be 10-20 and the gravitational wave background also is observable in the Planck satellite.