Perturbations in Symmetric Lee-Wick Bouncing Universe
  We investigate the tensor and the scalar perturbations in the symmetric
bouncing universe driven by one ordinary field and its Lee-Wick partner field
which is a ghost. We obtain the even- and the odd-mode functions of the tensor
perturbation in the matter-dominated regime. The tensor perturbation grows in
time during the contracting phase of the Universe, and decays during the
expanding phase. The power spectrum for the tensor perturbation is evaluated
and the spectral index is given by $n_{\rm T} =6$. We add the analysis on the
scalar perturbation by inspecting the even- and the odd-mode functions in the
matter-dominated regime, which was studied numerically in our previous work. We
conclude that the comoving curvature by the scalar perturbation is constant in
the super-horizon scale and starts to decay in the far sub-horizon scale while
the Universe expands.
