A Hamilton–Jacobi formalism for higher order implicit Lagrangians

Abstract

In this paper, we present a generalization of the Hamilton–Jacobi theory for higher order implicit Lagrangian systems. We propose two different backgrounds to deal with higher order implicit Lagrangian theories: the Ostrogradski approach and the Schmidt transform, which convert a higher order Lagrangian into a first order one. The Ostrogradski approach involves the addition of new independent variables to account for higher order derivatives, whilst the Schmidt transform adds gauge invariant terms to the Lagrangian function. In these two settings, the implicit character of the resulting equations will be treated in two different ways in order to provide a Hamilton–Jacobi equation. On one hand, the implicit Lagrangian system will be realized as a Lagrangian submanifold of a higher order tangent bundle that is generated by a Morse family. On the other hand, we will rely on the existence of an auxiliary section of a certain bundle that allows the construction of local vector fields, even if the differential equations are implicit. We will illustrate some examples of our proposed schemes, and discuss the applicability of the proposal.