We investigate the scale-dependence of f_NL in the self-interacting curvaton
model. We show that the scale-dependence, encoded in the spectral index
n_{f_NL}, can be observable by future cosmic microwave background observations,
such as CMBpol, in a significant part of the parameter space of the model. We
point out that together with information about the trispectrum g_NL, the
self-interacting curvaton model parameters could be completely fixed by
observations. We also discuss the scale-dependence of g_NL and its implications
for the curvaton model, arguing that it could provide a complementary probe in
cases where the theoretical value of n_{f_NL} is below observational
sensitivity.Comment: 14 pages, 5 figures, Eq.(10) correcte
