2015/01/23 by L. Lerman, Lerman, L., A. Markova +1
Mathematics · #37J10 #37J40 #37J45 #Dynamical Systems (math.DS) #FOS: Mathematics #math.DS #msc:37J10 #msc:37J40 #msc:37J45
paper · pdf · doi:10.48550/arxiv.1501.05935
39 pages, 4 figures
arxiv created 2015/01/23 · arxiv updated 2015/01/26
We study the orbit behavior of a four dimensional smooth symplectic diffeomorphism f near a homoclinic orbit Γ to an 1-elliptic fixed point under some natural genericity assumptions. 1-elliptic fixed point has two real eigenvalues out of unit circle and two others on the unit circle. Thus there is a smooth 2-dimensional center manifold Wc where the restriction of the diffeomorphism has the elliptic fixed point supposed to be generic (no strong resonances and first Birkhoff coefficient is nonzero). Moser's theorem guarantees the existence of a positive measure set of KAM invariant curves. Wc itself is a normally hyperbolic manifold in the whole phase space and due to Fenichel results every point on Wc has 1-dimensional stable and unstable smooth invariant curves forming two smooth foliations. In particular, each KAM invariant curve has stable and unstable smooth 2-dimensional invariant manifolds being Lagrangian. The related stable and unstable manifolds of Wc are 3-dimensional smooth manifolds which are supposed to be transverse along homoclinic orbit Γ. One of our theorems presents conditions under which each KAM invariant curve on Wc in a sufficiently small neighborhood of Γ has four transverse homoclinic orbits. Another result ensures that under some Birkhoff genericity assumption for the restriction of f on Wc saddle periodic orbits in resonance zones also have homoclinic orbits though its transversality or tangency cannot be verified directly.