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 {\it
Planck} and {\it 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_* \sim 0.0011 \pm 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 $\sim (8-11) /\lambda^{3/2} $ $m_{pl}$
during inflation where $\lambda \sim (1.0 \pm 0.5) N^{-2/5}$ 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
