Isoperiodic deformations of Toda curves and chains, the difference Korteweg - de Vries equation, and $SU(N)$ Seiberg-Witten theories
Vladimir Dragović, Vasilisa Shramchenko
TL;DR
The paper develops a comprehensive algebro-geometric framework for isoperiodic deformations of Toda curves and their higher-order generalizations. It constructs Toda families from Pell equation data, derives Rauch-based variational formulas, and obtains explicit isoperiodicity equations that govern the motion of dependent branch points, including generalized Toda families with $\Omega_\alpha$. The work connects these deformations to isospectral Jacobi problems, KdV difference equations, and SU($N$) Seiberg–Witten theories, showing how singular regimes and massless particles are preserved under isoperiodic flows. It also links equilibrium measures on interval unions to isoperiodic deformations and provides a concrete triangular solution to a constrained Schlesinger system, highlighting deep interactions between integrable systems, spectral theory, and gauge theory with explicit polynomial/Pell-structure underpinnings.
Abstract
We introduce the dynamics of Toda curves of order $N$ and derive differential equations governing this dynamics. We apply the obtained results to describe isoperiodic deformations of $N$-periodic Toda chains and periodic difference Korteweg-de Vries equation. We describe deformations of the essential spectra of $N$-periodic two-sided Jacobi matrices. We also study singular regimes of $SU(N)$ Seiberg-Witten theory and describe their deformations preserving the number of singularities where new massless particles may occur. We introduce and describe isoequilibrium deformations of arbitrary collections of $d$ real disjoint closed intervals. We conclude by providing explicit triangular solutions to constrained Schlesinger systems.
