Groups acts isometrically on proper hyperbolic complexes

Abstract: In this paper, we show that a group admits an affine action on some $L^p$-sapce with unbounded orbit for $p$ large enough, if it acts isometrically on a hyperbolic complex. As an application, we show that any isometric action of a group with property $F_\infty$ on a hyperbolic complex admits a bounded orbit.