FM 97-3 Title: Electric fields on a surface of constant negative curvature Authors: F. Bonetto, G. Gentile, V. Mastropietro Abstract: A one parameter family of time reversible Anosov flows is studied and shown to be dissipative, in the sense that the average volume contraction rate is positive and the Sinai-Ruelle-Bowen measure is singular with respect to the volume. Therefore the systems, physically describing a particle moving on a surface of constant negative curvature under the action of an electric field (corresponding to an automorphic form) and of a "thermostatting" force (given by Gauss' least constraint principle), verify the assumptions for the validity of the continuous time version of Gallavotti-Cohen's fluctuation theorem for the large fluctuations of the average volume contraction rate. If the surface genus is g>2 several independent electric fields can be considered and it makes sense to ask for the validity of Onsager's reciprocity: we show, by explicitly computing the relevant transport coefficients, that it is indeed obeyed. Dipartimento di Matematica, Universita' di Roma "La Sapienza", I-10085 Roma e-mail: bonetto@physics-sun.rockefeller.edu IHES, F-91440 Bures sur Yvette e-mail: gentileg@ipparco.roma1.infn.it Dipartimento di Matematica, Universita' di Roma "Tor Vergata", I-00133 Roma e-mail: vieri@ipparco.roma1.infn.it