1-loop Perturbative Corrections to the Matter and Galaxy Bispectrum with
  non-Gaussian Initial Conditions
  We derive the expressions for the 1-loop corrections in cosmological,
Eulerian, perturbation theory to the matter bispectrum and to the galaxy
bispectrum, assuming local galaxy bias, in presence of non-Gaussian initial
conditions. We compute them explicitly for the particular case of non-vanishing
initial bispectrum and trispectrum in the local model and for a non-vanishing
initial bispectrum alone for the equilateral model of primordial
non-Gaussianity. While the primordial contribution to the matter bispectrum for
values compatible with CMB observations is dominant over the component due to
gravitational instability at large scales, 1-loop perturbative corrections due
to non-Gaussian initial conditions correspond to just a few percent of the
gravity-induced bispectrum at mildly non-linear scales, similarly to what
happens for the matter power spectrum. However, in the perturbative expansion
for the galaxy bispectrum, 1-loop diagrams arising from non-linear bias are
responsible for significant large-scale contributions, indeed exceeding the
primordial component, both for the local and equilateral model. We study the
peculiar dependence on scale and on the shape of the triangular configurations
of such additional terms, similar in their origin to the large-scale
corrections to the halo and galaxy power spectra that raised significant
interest in the recent literature.
