Superhorizon Electromagnetic Field Background from Higgs Loops in
  Inflation
  If Higgs is a spectator scalar, i.e. if it is not directly coupled to the
inflaton, superhorizon Higgs modes must have been exited during inflation.
Since Higgs is unstable its decay into photons is expected to seed superhorizon
photon modes. We use in-in perturbation theory to show that this naive physical
expectation is indeed fulfilled via loop effects. Specifically, we calculate
the first order Higgs loop correction to the magnetic field power spectrum
evaluated at some late time after inflation. It turns out that this loop
correction becomes much larger than the tree-level power spectrum at the
superhorizon scales. This offers a mechanism to generate cosmologically
interesting superhorizon vector modes by scalar-vector interactions.
