F. Bonetto, V. Mastropietro Critical indices in a d=1 filled band Fermi system (311K, postscript) ABSTRACT. By renormalization group methods we obtain non perturbative results about a d=1 system of interacting spinless fermions in a periodic potential, if the conduction band is filled. Both the strength of the interaction and the amplitude of the periodic potential are assumed small. We obtain that the large distance asymptotic behavior of the two-point Schwinger function is anomalous and described by two critical indices, explicitly computed by convergent series, related to the renormalization of the spectral gap and of the discontinuity at the Fermi surface.