Arithmetic aspects of discrete periodic Toda flows
Bora Yalkinoglu
TL;DR
This work develops a new algebraic linearization of the discrete periodic Toda flow by embedding the dynamics into the Jacobian $\mathrm{Jac}(\mathcal{C})$ of the associated hyperelliptic spectral curve $\mathcal{C}$ via Mumford's representation. Time evolution becomes translation by a fixed divisor $\mathfrak{T}$ on $\mathrm{Jac}(\mathcal{C})$, with the Gauß–Cantor addition law encoding the discrete flow in purely algebraic terms, and the eigenvector map $\Psi_{\mathcal{C}}$ providing an explicit inverse Abel–Jacobi construction. The authors connect this algebraic framework to the periodic box-ball and tropical periodic Toda flows through tropicalization and a $q$-adic lift, yielding a natural integrality property: the flow can be defined over local rings $\mathbb{Z}[q]_{(q)}$, and passing to $q$-adic valuations recovers the box-ball dynamics as a $p$-adic limit. These results unify integrable dynamics with number-theoretic structures, enabling $p$-adic and tropical techniques to study division polynomials and offering a promising bridge to Berkovich spaces and further arithmetic-tropical interactions.
Abstract
We construct a new algebraic linearization of the discrete periodic Toda flow by using Mumford's algebraic description of the Jacobian of a hyperelliptic curve. In particular, the discrete periodic Toda flow can be expressed in terms of the famous Gauß composition law for quadratic forms adapted to the framework of hyperelliptic curves by Cantor. One surprising consequence of our approach is a new integrality property for the discrete periodic Toda flow which leads to a $p$-adic description of the closely related periodic box-ball flow, which has very surprising connections to number theory.
