Lagrangian Multiform for Cyclotomic Gaudin Models

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Main Authors: Caudrelier, Vincent, Singh, Anup Anand, Vicedo, Benoît
Format: Preprint
Published: 2024
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author Caudrelier, Vincent
Singh, Anup Anand
Vicedo, Benoît
author_facet Caudrelier, Vincent
Singh, Anup Anand
Vicedo, Benoît
contents We construct a Lagrangian multiform for the class of cyclotomic (rational) Gaudin models by formulating its hierarchy within the Lie dialgebra framework of Semenov-Tian-Shansky and by using the framework of Lagrangian multiforms on coadjoint orbits. This provides the first example of a Lagrangian multiform for an integrable hierarchy whose classical $r$-matrix is non-skew-symmetric and spectral parameter-dependent. As an important by-product of the construction, we obtain a Lagrangian multiform for the periodic Toda chain by choosing an appropriate realisation of the cyclotomic Gaudin Lax matrix. This fills a gap in the landscape of Toda models as only the open and infinite chains had been previously cast into the Lagrangian multiform framework. A slightly different choice of realisation produces the so-called discrete self-trapping (DST) model. We demonstrate the versatility of the framework by coupling the periodic Toda chain with the DST model and by obtaining a Lagrangian multiform for the corresponding integrable hierarchy.
format Preprint
id arxiv_https___arxiv_org_abs_2405_12837
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Lagrangian Multiform for Cyclotomic Gaudin Models
Caudrelier, Vincent
Singh, Anup Anand
Vicedo, Benoît
Mathematical Physics
High Energy Physics - Theory
Exactly Solvable and Integrable Systems
We construct a Lagrangian multiform for the class of cyclotomic (rational) Gaudin models by formulating its hierarchy within the Lie dialgebra framework of Semenov-Tian-Shansky and by using the framework of Lagrangian multiforms on coadjoint orbits. This provides the first example of a Lagrangian multiform for an integrable hierarchy whose classical $r$-matrix is non-skew-symmetric and spectral parameter-dependent. As an important by-product of the construction, we obtain a Lagrangian multiform for the periodic Toda chain by choosing an appropriate realisation of the cyclotomic Gaudin Lax matrix. This fills a gap in the landscape of Toda models as only the open and infinite chains had been previously cast into the Lagrangian multiform framework. A slightly different choice of realisation produces the so-called discrete self-trapping (DST) model. We demonstrate the versatility of the framework by coupling the periodic Toda chain with the DST model and by obtaining a Lagrangian multiform for the corresponding integrable hierarchy.
title Lagrangian Multiform for Cyclotomic Gaudin Models
topic Mathematical Physics
High Energy Physics - Theory
Exactly Solvable and Integrable Systems
url https://arxiv.org/abs/2405.12837