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arXiv · hep-th/9704090

Elliptic solutions to difference non-linear equations and related many-body problems

I. Krichever·P. Wiegmann·A. Zabrodin
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Abstract

We study algebro-geometric (finite-gap) and elliptic solutions of fully discretized KP or 2D Toda equations. In bilinear form they are Hirota's difference equation for $τ$-functions. Starting from a given algebraic curve, we express the $τ$-function and the Baker-Akhiezer function in terms of the Riemann theta function. We show that the elliptic solutions, when the $τ$-function is an elliptic polynomial, form a subclass of the general algebro-geometric solutions. We construct the algebraic curves of the elliptic solutions. The evolution of zeros of the elliptic solutions is governed by the discrete time generalization of the Ruijsenaars-Schneider many body system. The zeros obey equations which have the form of nested Bethe-Ansatz equations, known from integrable quantum field theories. We discuss the Lax representation and the action-angle-type variables for the many body system. We also discuss elliptic solutions to discrete analogues of KdV, sine-Gordon and 1D Toda equations and describe the loci of the zeros.

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I. Krichever, P. Wiegmann, A. Zabrodin. 1997-04-11. Elliptic solutions to difference non-linear equations and related many-body problems. https://doi.org/10.1007/s002200050333

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