Inflation in an external four-form gauge field
  We consider the possibility that the universe, viewed as a three-brane,
originated in a region of strong external field strength due to a four-form
gauge field in the bulk. It is shown that in a scenario of this kind inflation
is generic for a wide range of initial conditions. This is true even for small
field inflation with a simple quadratic inflaton potential, as well as for
Higgs potentials with the initial field well away from the local maximum, not
necessarily starting from rest. The power spectrum, spectral index, and $r$
parameter help to constrain parameters in this scenario, and $r<0.1$ favors
Higgs potentials.
