Action and rotation number of periodic orbits of area-preserving annulus diffeomorphisms
Huadi Qu
TL;DR
The paper generalizes Hutchings’ action-rotation results from the disk to the annulus for area-preserving diffeomorphisms. It develops a framework linking the action function, Calabi invariant, and rotation vectors, and uses a disk-augmentation technique to transfer estimates to the annulus, yielding lower bounds on mean action and rotation for periodic orbits under boundary rotations and flux. The results provide existence guarantees for periodic orbits with specified action and rotation properties and illustrate the theory with explicit examples and conjectural extensions. The work situates these results within the broader context of Reeb dynamics, ECH, and twist-type phenomena for invariant measures.
Abstract
We study periodic orbits for area-preserving surface diffeomorphisms, particularly some global properities related to the action function and rotation numbers. We generalize recent works of Machel Hutchings [4], proving the existence of periodic orbits with certain action and rotation values.
