Periodic solutions of the sinh-Gordon equation and integrable systems

TL;DR

This paper analyzes the space of periodic solutions to the sinh-Gordon equation using spectral data, framing it as an integrable system with Hamiltonians, and explores the geometric structures involved.

Contribution

It introduces a complete integrable system structure on the space of periodic sinh-Gordon solutions and links Hamiltonian gradients to Jacobi fields and Serre duality.

Findings

The space of solutions forms a completely integrable system.

Hamiltonian gradients relate to Jacobi fields from Pinkall-Sterling iteration.

The symplectic form connects to Serre duality.

Abstract

We study the space of periodic solutions of the elliptic $\sinh$-Gordon equation by means of spectral data consisting of a Riemann surface $Y$ and a divisor $D$. We show that the space $M_g^{\mathbf{p}}$ of real periodic finite type solutions with fixed period $\mathbf{p}$ can be considered as a completely integrable system $(M_g^{\mathbf{p}},\Omega,H_2)$ with a symplectic form $\Omega$ and a series of commuting Hamiltonians $(H_n)_{n \in \mathbb{N}}$. In particular we relate the gradients of these Hamiltonians to the Jacobi fields $(\omega_n)_{n\in \mathbb{N}_0}$ from the Pinkall-Sterling iteration. Moreover, a connection between the symplectic form $\Omega$ and Serre duality is established.