Possible evidence for Planck-scale resonant particle production during inflation from the CMB power spectrum

The power spectrum of the cosmic microwave background from both the Planck and WMAP data exhibits a slight dip for multipoles in the range of l = 10-30. We show that such a dip could be the result of the resonant creation of massive particles that couple to the inflaton field. For our best-fit models, the epoch of resonant particle creation reenters the horizon at a wave number of k(*) similar to 0.00011 +/- 0.0004 (h Mpc(-1)). The amplitude and location of this feature corresponds to the creation of a number of degenerate fermion species of mass similar to(8-11)/lambda(3/2) m(pl) during inflation where lambda similar to (1.0 +/- 0.5)N-2/5 is the coupling constant between the inflaton field and the created fermion species, while N is the number of degenerate species. Although the evidence is of marginal statistical significance, this could constitute new observational hints of unexplored physics beyond the Planck scale.