Signatures of non-Gaussianity in the curvaton model

We discuss the signatures of non-Gaussianity in the curvaton model where the potential includes also a non-quadratic term. In such a case the non-linearity parameter f NL can become very small, and we show that non-Gaussianity is then encoded in the non-reducible non-linearity parameter g NL of the trispectrum, which can be very large. Thus the place to look for the non-Gaussianity in the curvaton model may be the trispectrum rather than the bispectrum. We also show that g NL measures directly the deviation of the curvaton potential from the purely quadratic form. While g NL depends on the strength of the non-quadratic terms relative to the quadratic one, we find that for reasonable cases roughly – , which are values that may well be accessible by future observations.