Fine Features in the Primordial Power Spectrum
  A possible origin of the anomalous dip and bump in the primordial power spectrum, which are reconstructed from WMAP data corresponding to the multipole $\ell=100\sim 140$ by using the inversion method, is investigated as a consequence of modification of scalar field dynamics in the inflation era. Utilizing an analytic formula to handle higher order corrections to the slow-roll approximation, we evaluate the relation between a detailed shape of inflaton potential and a fine structure in the primordial power spectrum. We conclude that it is unlikely to generate the observed dip and bump in the power spectrum by adding any features in the inflaton potential. Though we can make a fine enough shape in the power spectrum by controlling the feature of the potential, the amplitude of the dip and bump becomes too small in that case. 
Kohei Kumazaki, Shuichiro Yokoyama and Naoshi Sugiyama
astro-ph.CO gr-qc hep-ph hep-th