Impact of other scalar fields on oscillons after hilltop inflation
  Oscillons are spatially localized and relatively stable field fluctuations
which can form after inflation under suitable conditions. In order to reheat
the universe, the fields which dominate the energy density after inflation have
to couple to other degrees of freedom and finally produce the matter particles
present in the universe today. In this study, we use lattice simulations in 2+1
dimensions to investigate how such couplings can affect the formation and
stability of oscillons. We focus on models of hilltop inflation, where we have
recently shown that hill crossing oscillons generically form, and consider the
coupling to an additional scalar field which, depending on the value of the
coupling parameter, can get resonantly enhanced from the inhomogeneous inflaton
field. We find that three cases are realized: without a parametric resonance,
the additional scalar field has no effects on the oscillons. For a fast and
strong parametric resonance of the other scalar field, oscillons are strongly
suppressed. For a delayed parametric resonance, on the other hand, the
oscillons get imprinted on the other scalar field and their stability is even
enhanced compared to the single-field oscillons.
