2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/55728We show equivalence between the massive Thirring model and the sine-Gordon theory by gauge fixing a wider gauge invariant theory in two different ways. The exact derivation of the equivalence hinges on the existence of an underlying conformal symmetry. Previous derivations were all perturbative in mass (althought to all orders).5 pages, Latex 2e, Lectures given at 11th Yugoslav Symposium on Nuclear and Particle Physics, Studenica, September 1998High Energy Physics - Theorytext