I encountered this notation in a paper by Carron:
When X = $\Gamma{\setminus}\mathbb{H}^n$ is a real hyperbolic manifold, ...
$\Gamma$ is a discrete torsion free subgroup of SO$(n,1)$. My question is narrow: what is the meaning of the backslash notation? It is specifically used without spaces, i.e., not $\Gamma \setminus \mathbb{H}^n$. Thanks for clarifying!