Bambusi D., Vella D.
Quasi periodic breathers in Hamiltonian lattices with symmetries
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ABSTRACT.  We prove existence of quasiperiodic breathers in
Hamiltonian lattices of weakly coupled oscillators having some
integrals of motion independent of the Hamiltonian. The proof is
obtained by constructing quasiperiodic breathers in the anticontinuoum
limit and using a recent theorem by N.N. Nekhoroshev \cite{N} as
extended in \cite{BG} to continue them to the coupled
case. Applications to several models are given.