  The existence of planets orbiting a central binary star system immediately
raises questions regarding their formation and dynamical evolution. Recent
discoveries of circumbinary planets by the Kepler space telescope has shown
that some of these planets reside close to the dynamical stability limit where
it is very difficult to form planets in situ. For binary systems with nearly
circular orbits, such as Kepler-38, the observed proximity of planetary orbits
to the stability limit can be understood by an evolutionary process in which
planets form farther out in the disk and migrate inward to their observed
position. The Kepler-34 system has a high orbital eccentricity of 0.52. Here,
we analyse evolutionary scenarios for the planet observed around this system
using two-dimensional hydrodynamical simulations.
  The highly eccentric binary opens a wide inner hole in the disk which is also
eccentric, and displays a slow prograde precession. As a result of the large,
eccentric inner gap, an embedded planet settles in a final equilibrium position
that lies beyond the observed location of Kepler-34 b, but has the correct
eccentricity. In this configuration the planetary orbit is aligned with the
disk in a state of apsidal corotation.To account for the closer orbit of
Kepler-34 b to the central binary, we considered a two-planet scenario and
examined the evolution of the system through joint inward migration and capture
into mean-motion resonances. When the inner planet orbits inside the gap of the
disk, planet-planet scattering ensues. While often one object is thrown into a
large, highly eccentric orbit, at times the system is left with a planet close
to the observed orbit, suggesting that Kepler 34 might have had two
circumbinary planets where one might have been scattered out of the system or
into an orbit where it did not transit the central binary during the operation
of Kepler.
