  We say that a finitely generated group $G$ has property (QT) if it acts
isometrically on a finite product of quasi-trees so that orbit maps are
quasi-isometric embeddings. A quasi-tree is a connected graph with path metric
quasi-isometric to a tree, and product spaces are equipped with the
$\ell^1$-metric.
  As an application of the projection complex techniques, we prove that
residually finite hyperbolic groups and mapping class groups have (QT).
