The translation number and quasi-morphisms on groups of symplectomorphisms of the disk
arXiv:1912.10863
Abstract
On groups of symplectomorphisms of the disk, we construct two homogeneous quasi-morphisms which relate to the Calabi invariant and the flux homomorphism respectively. We also show the relation between the quasi-morphisms and the translation number introduced by Poincaré.
9 pages, to appear in Ann. Inst. Fourier (Grenoble)