Exploring the Superimposed Oscillations Parameter Space
  The space of parameters characterizing an inflationary primordial power spectrum with small superimposed oscillations is explored using Monte Carlo methods. The most interesting region corresponding to high frequency oscillations is included in the analysis. The oscillations originate from some new physics taking place at the beginning of the inflationary phase and characterized by the new energy scale Mc. It is found that the standard slow-roll model remains the most probable one given the first year WMAP data. At the same time, the oscillatory models better fit the data on average, which is consistent with previous works on the subject. This is typical of a situation where volume effects in the parameter space play a significant role. Then, we find the amplitude of the oscillations to be less than 22% of the mean amplitude and the new scale Mc to be such that H/Mc < 6.6 x 10^(-4) at 1-sigma level, where H is the scale of inflation. 
Jerome Martin and Christophe Ringeval