Kahler moduli double inflation
  We show that double inflation is naturally realized in K\"ahler moduli
inflation, which is caused by moduli associated with string compactification.
We find that there is a small coupling between the two inflatons which leads to
amplification of perturbations through parametric resonance in the intermediate
stage of double inflation. This results in the appearance of a peak in the
power spectrum of the primordial curvature perturbation. We numerically
calculate the power spectrum and show that the power spectrum can have a peak
on observationally interesing scales. We also compute the TT-spectrum of CMB
based on the power spectrum with a peak and see that it better fits WMAP
7-years data.
