  We analyze the limits on resonant particle production during inflation based
upon the power spectrum of fluctuations in matter and the cosmic microwave
background. We show that such a model is consistent with features observed in
the matter power spectrum deduced from galaxy surveys and damped Lyman-alpha
systems at high redshift. It also provides an alternative explanation for the
excess power observed in the power spectrum of the cosmic microwave background
fluctuations in the range of 1000 < l < 3500. For our best-fit models, epochs
of resonant particle creation reenter the horizon at wave numbers ~ 0.4 and/or
0.2 (h/Mpc). The amplitude and location of these features correspond to the
creation of fermion species of mass ~ 1-2 Mpl during inflation with a coupling
constant between the inflaton field and the created fermion species of near
unity. Although the evidence is marginal, if this interpretation is correct,
this could be one of the first observational hints of new physics at the Planck
scale.
