Compressible binormal equation for membranes

Determine an interesting, possibly integrable in lower dimensions, analog of the binormal equation for membranes in the compressible setting of augmented triples on a Riemannian manifold.

Background

The paper develops a generalized Marsden–Weinstein symplectic structure on singular 1-form densities, represented by augmented triples (Γ,ρ,α)(\Gamma,\rho,\alpha), as a compressible-fluid counterpart of the classical Marsden–Weinstein structure for incompressible vortex membranes. In the incompressible setting, the length or volume Hamiltonian generates the binormal or skew-mean-curvature evolution.

For augmented triples, the authors explain that a seemingly natural volume Hamiltonian is insufficient because the generalized Hamiltonian structure depends on first jets of the Hamiltonian, equivalently second jets of the associated vector field near Γ\Gamma. They therefore leave unresolved the construction of a suitable compressible analog of binormal dynamics, including the possibility of integrable cases in low dimensions.

References

Here are several open questions related to the introduction of symplectic structures on the augmented triples.

  1. What could be an interesting (and possible integrable in lower dimensions) analog of the binormal equation for membranes in this compressible setting?
— Generalized Marsden-Weinstein symplectic structures  (2610.01401 - Khesin et al., 1 Oct 2026) in Section "Dynamics on membranes and open questions", subsection "The binormal equation and its analogs" (Section 5.1)