New Shapes of Primordial Non-Gaussianity from Quasi-Single Field
  Inflation with Multiple Isocurvatons
  We study a simple extension of quasi-single field inflation in which the
inflaton interacts with multiple extra massive scalars known as isocurvatons.
Due to the breaking of time translational invariance by the inflaton
background, the theory includes kinetic mixings among the inflaton and
isocurvatons. These mixings give rise to novel new features in the primordial
non-Gaussianities of the scalar curvature perturbation. A noteworthy feature is
the amplitude of the squeezed bispectrum can grow nearly as $(k_s/k_l)^{-3}$
while oscillating as ${\rm \cos\gamma \log}(k_s/k_l)$, where $k_s/k_l$ is the
ratio of the lengths of the short and long wavevectors. Observation of such a
shape would provide evidence for the existence of multiple isocurvatons during
inflation. In addition, we consider the effects of these non-Gaussianities on
large-scale structure.
