Primordial perturbations with pre-inflationary bounce
  Based on the effective field theory (EFT) of nonsingular cosmologies, we
build a stable model, without the ghost and gradient instabilities, of bounce
inflation (inflation is preceded by a cosmological bounce). We perform a full
simulation for the evolution of scalar perturbation, and find that the
perturbation spectrum has a large-scale suppression (as expected), which is
consistent with the power deficit of the cosmic microwave background (CMB)
TT-spectrum at low multipoles, but unexpectedly, it also shows itself one
marked lower valley, which actually provides a better fit to the dip at
multipole $l\sim 20$. The depth of valley is relevant with the physics around
the bounce scale, which is model-dependent.
