  Oscillons are massive, long-lived, localized excitations of a scalar field.
We show that in a large class of well-motivated single-field models, inflation
is followed by self-resonance, leading to copious oscillon generation and a
lengthy period of oscillon domination. These models are characterized by an
inflaton potential which has a quadratic minimum and is shallower than
quadratic away from the minimum. This set includes both string monodromy models
and a class of supergravity inspired scenarios, and is in good agreement with
the current central values of the concordance cosmology parameters. We assume
that the inflaton is weakly coupled to other fields, so as not to quickly drain
energy from the oscillons or prevent them from forming. An oscillon-dominated
universe has a greatly enhanced primordial power spectrum on very small scales
relative to that seen with a quadratic potential, possibly leading to novel
gravitational effects in the early universe.
