Non-Gaussian fingerprints of self-interacting curvaton

We investigate non-Gaussianities in self-interacting curvaton models treating both renormalizable and non-renormalizable polynomial interactions. We scan the parameter space systematically and compute numerically the non-linearity parameters f(NL) and g(NL). We find that even in the interaction dominated regime there are large regions consistent with current observable bounds. Whenever the interactions dominate, we discover significant deviations from the relations f(NL) similar to r(dec)(-1) and g(NL) similar to r(dec)(-1) valid for quadratic curvaton potentials, where r(dec) measures the curvaton contribution to the total energy density at the time of its decay. Even if r(dec) << 1, there always exists regions with f(NL) similar to 0 since the sign of f(NL) oscillates as a function of the parameters. While g(NL) can also change sign, typically g(NL) is non-zero in the low-f(NL) regions. Hence, for some parameters the non-Gaussian statistics is dominated by g(NL) rather than by f(NL). Due to self-interactions, both the relative signs of f(NL) and g(NL) and the functional relation between them is typically modified from the quadratic case, offering a possible experimental test of the curvaton interactions.