  We explore the effect of a cubic correction gnl*phi^3 on the mass function
and bias of dark matter haloes extracted from a series of large N-body
simulations and compare it to theoretical predictions. Such cubic terms can be
motivated in scenarios like the curvaton model, in which a large cubic
correction can be produced while simultaneously keeping the quadratic fnl*phi^2
correction small. The deviation from the Gaussian halo mass function is in
reasonable agreement with the theoretical predictions. The scale-dependent bias
correction Delta b_kappa(k,gnl) measured from the auto- and cross-power
spectrum of haloes, is similar to the correction in fnl models, but the
amplitude is lower than theoretical expectations. Using the compilation of LSS
data in Slosar et al. (2008), we obtain for the first time a limit on gnl of
-3.5*10^5 < gnl < +8.2*10^5 (at 95% CL). This limit will improve with the
future LSS data by 1-2 orders of magnitude, which should test many of the
scenarios of this type.
