2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/198744We consider the N-soliton solutions in the sine-Gordon model as a N-body problem. This leads to a relativistic generalization of the Calogero model first introduced by Ruijsenaars. We show that the fundamental Poisson bracket of the Lax matrix is quadratic, and the $r$-matrix is a dynamical one. This is in contrast to the Calogero model where the fundamental Poisson bracket of the Lax matrix is linear.10 pages LATEX SPhT-93-072; LPTHE-93-40High Energy Physics - Theorytext