The hyperbolic BC(n) Sutherland and the rational BC(n)   Ruijsenaars-Schneider-van Diejen models: Lax matrices and duality
  In this paper, we construct canonical action-angle variables for both the hyperbolic BC(n) Sutherland and the rational BC(n) Ruijsenaars-Schneider-van Diejen models with three independent coupling constants. As a byproduct of our symplectic reduction approach, we establish the action-angle duality between these many-particle systems. The presented dual reduction picture builds upon the construction of a Lax matrix for the BC(n)-type rational Ruijsennars-Schneider-van Diejen model. 
B.G. Pusztai
math-ph hep-th math.MP math.SG