Generic Bifurcation of Hamiltonian Vector Fields with Symmetry
Dellnitz, M., I. Melbourne and J. E. Marsden
Nonlinearity, 5, 979-996
Abstract:
One of the goals of this paper is to describe explicitly the generic movement of eigenvalues
through a one-to-one resonance in a (linearized) Hamiltonian system. We classify this movement, and
hence answer the question of when the collisions are "dangerous" in the sense of Krein by
using a combination of group theory and definiteness properties of the associated quadratic
Hamiltonian. For example, for systems with S1 symmetry, if the representation on an
associated four dmensional symplectic space consists of two complex dual subspaces, then generically
the eigenvalues split if the Hamiltonian is indefinite, and they pass if the Hamiltonian is
definite. The result is to be contrasted with the bifurcation of steady states (zero eigenvalue)
where one can use either group theory alone (Golubitsky and Stewart) or definiteness properties of
the Hamiltonian (Cartan-Oh) to determine if the eigenvalues split or pass on the imaginary axis.
The results are illustrated for the rotating orthogonal double planar pendulum.