  Approximately half of the planets discovered by NASA's Kepler mission are in
systems where just a single planet transits its host star, and the remaining
planets are observed to be in multi-planet systems. Recent analyses have
reported a dichotomy in the eccentricity distribution displayed by systems
where a single planet transits compared with that displayed by the multi-planet
systems. Using $N$-body simulations, we examine the hypothesis that this
dichotomy has arisen because inner systems of super-Earths are frequently
accompanied by outer systems of giant planets that can become dynamically
unstable and perturb the inner systems. Our initial conditions are constructed
using a subset of the known Kepler five-planet systems as templates for the
inner systems, and systems of outer giant planets with masses between those of
Neptune and Saturn that are centred on orbital radii $2 \le a_{\rm p} \le 10$
au. The parameters of the outer systems are chosen so that they are always
below an assumed radial velocity detection threshold of 3 ms$^{-1}$. The
results show an inverse relation between the mean eccentricities and the
multiplicites of the systems. Performing synthetic transit observation of the
final systems reveals dichotomies in both the eccentricity and multiplicity
distributions that are close to being in agreement with the Kepler data. Hence,
understanding the observed orbital and physical properties of the compact
systems of super-Earths discovered by Kepler may require holistic modelling
that couples the dynamics of both inner and outer systems of planets during and
after the epoch of formation.
