  We derive a formula for the halo/galaxy bispectrum on the basis of the
integrated Perturbation Theory (iPT). In addition to the gravity-induced
non-Gaussianity, we consider the non-Gaussianity of the primordial curvature
perturbations, and investigate in detail the effect of such primordial
non-Gaussianity on the large-scale halo/galaxy bispectrum. In iPT, the effects
of primordial non-Gaussianity are wholly encapsulated in the linear
(primordial) polyspectra, and we systematically calculate the contributions to
the large-scale behaviors arising from the three types of primordial bispectrum
(local-, equilateral-, and orthogonal-types), and primordial trispectrum of the
local-type non-Gaussianity. We find that the equilateral- and orthogonal-type
non-Gaussianities show distinct scale-dependent behaviors which can dominate
the gravity-induced non-Gaussianity at very large scales. For the local-type
non-Gaussianity, higher-order loop corrections are found to give a
significantly large contribution to the halo/galaxy bispectrum of the squeezed
shape, and eventually dominate over the other contributions on large scales. A
diagrammatic approach based on the iPT helps us to systematically investigate
an impact of such higher-order contributions to the large-scale halo/galaxy
bispectrum.
