  The results of large-scale exoplanet transit surveys indicate that the
distribution of small planet radii is likely sculpted by atmospheric loss.
Several possible physical mechanisms exist for this loss of primordial
atmospheres, each of which produces a different set of observational
signatures. In this study, we investigate the impact-driven mode of atmosphere
loss via N-body simulations. We compare the results from giant impacts, at a
demographic level, to results from another commonly-invoked method of
atmosphere loss: photoevaporation. Applying two different loss prescriptions to
the same sets of planets, we then examine the resulting distributions of
planets with retained primordial atmospheres. As a result of this comparison,
we identify two new pathways toward discerning the dominant atmospheric loss
mechanism at work. Both of these pathways involve using transit multiplicity as
a diagnostic, in examining the results of follow-up atmospheric and radial
velocity surveys.
