Smooth Models of Fibered Partially Hyperbolic Systems

We study fibered partially hyperbolic diffeomorphisms. We show that as long as certain topological obstructions vanish and as long as homological minimum expansion dominates the distortion on the fibers that a fibered partially hyperbolic system can be homotoped to a fibered partially hyperbolic system with a $C^{\infty}$-center fibering. In addition, we study obstructions to the existence of smooth lifts of Anosov diffeomorphisms to bundles. In particular, we give an example of smooth topologically trivial bundle over a torus, where an Anosov diffeomorphism can lift continuously but not smoothly to the bundle.