title: Critical number in scattering and escaping problems in classical mechanics.
abstract: Scattering and escaping problems for Hamiltonian systems with two degrees of freedom of the type kinetic plus potential energy arise in many applications. Under some discrete symmetry assumptions, it is shown that important quantities in these problems are determined by a relation between two canonical invariant numbers that can be explicitly computed.
authors.affiliation: Instituto de Matemática e Estatística, Universidade de São Paulo, R. do Matão 1010, CEP 05508-900, São Paulo-SP, Brazil. szanta@math.princeton.edu
authors.forename: S
authors.initials: S
authors.lastname: Addas-Zanata
authors.forename: C
authors.initials: C
authors.lastname: Grotta-Ragazzo