TITLE: Arnold diffusion in perturbations of analytic integrable Hamiltonian systems AUTHORS: Ernest Fontich Departament de Matematica Aplicada i Analisi Universitat de Barcelona Gran Via, 585, 08007 Barcelona, Spain fontich@cerber.mat.ub.es Pau Martin Departament de Matematica Aplicada i Telematica Universitat Politecnica de Catalunya Ed-C3, Jordi Girona, 1-3, 08034 Barcelona Spain martin@mat.upc.es ABSTRACT: Given an analytic integrable Hamiltonian with three or more degrees of freedom, we construct, arbitrarily close to it, an analytic perturbation with transition chains whose lengths only depend on the unperturbed Hamiltonian. Then we deduce that the perturbed system has Arnold diffusion. We provide the technical details of the tools we use.