Scaling Symmetries and Conformal Relative Equilibria on Poisson Manifolds, with Applications to Lie--Poisson Systems

TL;DR

This paper studies conformal relative equilibria in Hamiltonian systems on Poisson manifolds with scaling symmetries, providing algebraic criteria and classifications, especially for Lie--Poisson systems like Bianchi types.

Contribution

It introduces conformally Poisson actions and momentum maps, characterizes equilibria via augmented Hamiltonians, and classifies three-dimensional cases using Lie algebra properties.

Findings

Conformal relative equilibria exist if and only if the Lie algebra has a hyperbolic element.

Complete classification of 3D cases via Bianchi classification.

Obstructions to equilibria in classical rigid body dynamics on so(3)^*.

Abstract

We investigate conformal relative equilibria for Hamiltonian systems on exact Poisson manifolds equipped with scaling symmetries. By introducing conformally Poisson actions and conformal momentum maps, we characterize these equilibria through an augmented Hamiltonian formulation; in the nondegenerate case, this recovers the conditions recently developed for the exact symplectic case. Specializing to Lie--Poisson manifolds, where the natural scaling action canonically provides an exact Poisson structure on the dual of any finite-dimensional Lie algebra, we establish a purely algebraic criterion: a homogeneous Hamiltonian system admits a nontrivial conformal relative equilibrium if and only if the underlying Lie algebra contains a hyperbolic element. This yields a complete classification in dimension three via the Bianchi classification. As a prominent application, we show that nontrivial conformal relative equilibria emerge in the dynamics on $\mathfrak{so}(2,1)^*$, but are strictly obstructed for the classical free rigid body on $\mathfrak{so}(3)^*$.