  We present general existence and uniqueness results for marked models with
pair interactions, exemplified through Gibbs point processes on path space.
More precisely, we study a class of infinite-dimensional diffusions under
Gibbsian interactions, in the context of marked point configurations: the
starting points belong to $\mathbb{R}^d$, and the marks are the paths of
Langevin diffusions. We use the entropy method to prove existence of an
infinite-volume Gibbs point process and use cluster expansion tools to provide
an explicit activity domain in which uniqueness holds.
