title: Degenerate periodic orbits and homoclinic torus bifurcation.
abstract: A one-parameter family of periodic orbits with frequency omega and energy E of an autonomous Hamiltonian system is degenerate when E'(omega) = 0. In this paper, new features of the nonlinear bifurcation near this degeneracy are identified. A new normal form is found where the coefficient of the nonlinear term is determined by the curvature of the energy-frequency map. An important property of the bifurcating "homoclinic torus" is the homoclinic angle and a new asymptotic formula for it is derived. The theory is constructive, and so is useful for physical applications and in numerics.
authors.affiliation: Department of Mathematics, University of Surrey, Guildford, England, UK. T.Bridges@surrey.ac.uk
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Bridges
authors.forename: Neil M
authors.initials: NM
authors.lastname: Donaldson