Special Session 94: Dynamics and Variational Methods of Quasi-Hamiltonian Systems

Cartan-Schouten Connections: Geometric Reduction and a Connection-Dependent Variational Principle
Qiao Huang
Southeast University
Peoples Rep of China
Co-Author(s):    
Abstract:
We study the family of Cartan-Schouten connections on Lie groups, parameterized by $\lambda\in[0,1]$, whose geodesics through the identity are one-parameter subgroups. We compute their curvature, torsion, parallel transport, and geodesics, and develop Euler-Poincar\'e and Lie-Poisson reduction for mechanical systems via these connections, unifying the ``minus'' and ``plus'' cases. These inspire us to introduce a connection-dependent variational principle where the Lagrangian is expressed in terms of the parallel-transported velocity, leading to an integro-differential Euler-Lagrange equation that explicitly involves torsion and curvature memory terms.