Arithmeticity for Smooth Maximal Rank Positive Entropy Actions of $\mathbb{R}^k$
De Alp Uzman
We prove an arithmeticity theorem in the context of nonuniform measure rigidity. Adapting machinery developed by A. Katok and F. Rodriguez Hertz [J. Mod. Dyn. 10 (2016), 135–172; MR3503686] for $\mathbb{Z}^k$ systems to $\mathbb{R}^k$ systems, we show that any maximal rank positive entropy system on a manifold generated by $k>=2$ commuting vector fields of regularity $\mathbb{C}^k$ for $r>1$ is measure theoretically isomorphic to a constant time change of the suspension of some action of $\mathbb{Z}^k$ on the $(k+1)$-torus or the $(k+1)$-torus modulo {id,-id} by affine automorphisms with linear parts hyperbolic. Further, the constructed conjugacy has certain smoothness properties. This in particular answers a problem and a conjecture from a prequel paper of Katok and Rodriguez Hertz, joint with B. Kalinin [Ann. of Math. (2) 174 (2011), no. 1, 361–400; MR2811602].