  The population of non magnetic cataclysmic variables evolving under the
influence of a circumbinary disk is investigated for systems above the upper
edge of the period gap at orbital periods greater than 2.75hr. For a fractional
mass input rate into the disk, corresponding to 3e-4 of the mass transfer rate,
the model systems exhibit a bounce at orbital periods greater than 2.75hr. The
simulations reveal that (1) some systems can exist as dwarf nova type systems
throughout their lifetime, (2) dwarf nova type systems can evolve into
nova-like systems as their mass transfer rate increases with increasing
circumbinary disk mass, and (3) nova-like systems can evolve back into dwarf
nova systems during their postbounce evolution to longer orbital periods. Among
these subclasses, nova-like cataclysmic variables would be the best candidates
to search for circumbinary disks at wavelengths greater than 10 micron. The
theoretical orbital period distribution of our population synthesis model is in
reasonable accord with the combined population of dwarf novae and nova-like
systems above the period gap, suggesting the possibility that systems with
unevolved donors need not detach and evolve below the period gap as in the
disrupted magnetic braking model. The resulting population furthermore reveals
the possible presence of systems with small mass ratios (a property of systems
exhibiting superhump phenomena at long orbital periods) and a preference of
O/Ne/Mg white dwarfs in dwarf nova systems in comparison to nova-like systems.
The importance of observational bias in accounting for the differing
populations is examined, and it is shown that an understanding of these effects
is necessary in order to confront the theoretical distributions with the
observed ones in a meaningful manner. (abridged)
