The Decay of the Standard Model Higgs after Inflation
  We study the nonperturbative dynamics of the Standard Model (SM) after
inflation, in the regime where the SM is decoupled from (or weakly coupled to)
the inflationary sector. We use classical lattice simulations in an expanding
box in (3+1) dimensions, modeling the SM gauge interactions with both global
and Abelian-Higgs analogue scenarios. We consider different post-inflationary
expansion rates. During inflation, the Higgs forms a condensate, which starts
oscillating soon after inflation ends. Via nonperturbative effects, the
oscillations lead to a fast decay of the Higgs into the SM species,
transferring most of the energy into $Z$ and $W^{\pm}$ bosons. All species are
initially excited far away from equilibrium, but their interactions lead them
into a stationary stage, with exact equipartition among the different energy
components. From there on the system eventually reaches equilibrium. We have
characterized in detail, in the different expansion histories considered, the
evolution of the Higgs and of its dominant decay products, until equipartition
is established. We provide a useful mapping between simulations with different
parameters, from where we derive a master formula for the Higgs decay time, as
a function of the coupling constants, Higgs initial amplitude and
postinflationary expansion rate.
