Dynamical similarity in higher-order classical symplectic systems

Many theories of physical interest, which admit a Hamiltonian description, exhibit symmetries under a particular class of nonstrictly conformal transformation, known as dynamical similarities. The presence of such symmetries allows a reduction process to be carried out, eliminating a single degree of freedom from the system, which we associate with an overall scale. This process of “contact reduction” leads to theories of a frictional nature, in which the physically observable quantities form an autonomous subsystem, that evolves in a predictable manner. We demonstrate that this procedure has a natural generalization to theories of higher order; detailed examples are provided, and physical implications discussed.