Transition To Order After Hilltop Inflation
  We investigate the rich nonlinear dynamics during the end of hilltop
inflation by numerically solving the coupled Klein-Gordon-Friedmann equations
in a expanding universe. In particular, we search for coherent, nonperturbative
configurations that may emerge due to the combination of nontrivial couplings
between the fields and resonant effects from the cosmological expansion. We
couple a massless field to the inflaton to investigate its effect on the
existence and stability of coherent configurations and the effective equation
of state at reheating. For parameters consistent with data from the Planck and
WMAP satellites, and for a wide range of couplings between the inflaton and the
massless field, we identify a transition from disorder to order characterized
by emergent oscillon-like configurations. We verify that these configurations
can contribute a maximum of roughly 30% of the energy density in the universe.
At late times their contribution to the energy density drops to about 3%, but
they remain long-lived on cosmological time-scales, being stable throughout our
simulations. Cosmological oscillon emergence is described using a new measure
of order in field theory known as relative configurational entropy.
