http://arxiv.org/abs/1311.2552
We perform a search for localized oscillatory features in the Planck CMB power spectrum, assuming they are caused by a transient reduction in the speed of sound of the adiabatic mode during effectively single-field, uninterrupted slow-roll inflation. We find several fits, for which we calculate the expected correlated signal in the primordial bispectrum, and compare it to the search for scale dependent bispectrum features carried out by the Planck collaboration. Where both searches overlap, we reproduce the Planck results reasonably well. In addition, some of our best fits lie outside the scales and frequency ranges surveyed by Planck, which calls for an extension in frequencies and envelopes of the templates used in Planck’s search. By exploiting correlations between different observables, our results strongly suggest that current data might already be sensitive enough to detect transient reductions in the speed of sound as mild as a few percent, opening a new window for the presence of extra degrees of freedom during inflation.
Tue, 12 Nov 13
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