Poisson reductions of master integrable systems on doubles of compact Lie groups

TL;DR

This paper studies Poisson reductions of integrable systems on doubles of compact Lie groups, deriving explicit formulas and unifying various models including spin Sutherland and Ruijsenaars--Schneider systems.

Contribution

It provides a unified framework for reducing integrable systems on classical doubles, revealing new models and connecting known ones through explicit Poisson structures.

Findings

Derived explicit reduced Poisson structures and equations of motion.

Connected reduced systems to classical dynamical r-matrices.

Included new models and examples of known integrable systems.

Abstract

We consider three 'classical doubles' of any semisimple, connected and simply connected compact Lie group $G$: the cotangent bundle, the Heisenberg double and the internally fused quasi-Poisson double. On each double we identify a pair of 'master integrable systems' and investigate their Poisson reductions. In the simplest cotangent bundle case, the reduction is defined by taking quotient by the cotangent lift of the conjugation action of $G$ on itself, and this naturally generalizes to the other two doubles. In each case, we derive explicit formulas for the reduced Poisson structure and equations of motion and find that they are associated with well known classical dynamical $r$-matrices. Our principal result is that we provide a unified treatment of a large family of reduced systems, which contains new models as well as examples of spin Sutherland and Ruijsenaars--Schneider models that were studied previously. We argue that on generic symplectic leaves of the Poisson quotients the reduced systems are integrable in the degenerate sense, although further work is required to prove this rigorously.