  We consider the description of the clustering of halos for
physically-motivated types of non-Gaussian initial conditions. In particular we
include non-Gaussianity of the type arising from single field slow-roll, multi
fields, curvaton (local type), higher-order derivative-type (equilateral),
vacuum-state modifications (enfolded-type) and horizon-scale GR corrections
type. We show that large-scale halo bias is a very sensitive tool to probe
non-Gaussianity, potentially leading, for some planned surveys, to a detection
of non-Gaussianity arising from horizon-scale GR corrections. In tandem with
cosmic microwave background constraints, the halo-bias approach can help
enormously to discriminate among different shapes of non-Gaussianity and thus
among models for the origin of cosmological perturbations.
