Properties of oscillons in hilltop potentials: energies, shapes, and
  lifetimes
  Oscillons are spatially localised strong fluctuations of a scalar field. They
can e.g. form after inflation when the scalar field potential is shallower than
quadratic away from the minimum. Although oscillons are not protected by
topology, they can be remarkably stable and have a significant impact on the
(p)reheating phase. In this work we investigate the properties of oscillons in
hilltop-shaped potentials, in particular the typical energies, shapes and
lifetimes. In the first part of the paper, we simulate oscillon creation and
stabilization with (3+1)-dimensional classical lattice simulations, and extract
the typical energies, radii and amplitudes of the oscillons. In the second part
we approximate the oscillons as spherically symmetric, and simulate single
oscillons until their decay. We find that typical oscillons live up to about
4-5 e-folds, with the individual lifetime of the oscillons depending mainly on
the initial shape of the oscillon and the power-law coefficient characterising
the particular hilltop model. We also observe a breathing mode in the oscillon
radii and amplitudes, and find that stronger breathing implies shorter
lifetimes.
