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

Abstract

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_*∼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 ∼(8 - 11 )/λ^{3 /2} m_{p l} during inflation where λ ∼(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.