Mapping partition functions

Fuente: arXiv
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Main Authors: Yang, Di, Zagier, Don
Format: Preprint
Published: 2023
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author Yang, Di
Zagier, Don
author_facet Yang, Di
Zagier, Don
contents We introduce an infinite group action on partition functions of WK type, meaning of the type of the partition function $Z^{\rm WK}$ in the famous result of Witten and Kontsevich expressing the partition function of $ψ$-class integrals on the compactified moduli space $\overline{\mathcal{M}}_{g,n}$ as a $τ$-function for the Korteweg--de Vries hierarchy. Specifically, the group which acts is the group $\mathcal{G}$ of formal power series of one variable $φ(V)=V+O(V^2)$, with group law given by composition, acting in a suitable way on the infinite tuple of variables of the partition functions. In particular, any $φ\in \mathcal{G}$ sends the Witten--Kontsevich (WK) partition function $Z^{\rm WK}$ to a new partition function $Z^φ$, which we call the WK mapping partition function associated to $φ$. We show that the genus zero part of $\log Z^φ$ is independent of $φ$ and give an explicit recursive description for its higher genus parts (loop equation), and as applications of this obtain relationships of the $ψ$-class integrals to Gaussian Unitary Ensemble and generalized Brézin--Gross--Witten correlators. In a different direction, we use $Z^φ$ to construct a new integrable hierarchy, which we call the WK mapping hierarchy associated to $φ$. We show that this hierarchy is a bihamiltonian perturbation of the Riemann--Hopf hierarchy possessing a $τ$-structure, and prove that it is a universal object for all such perturbations. Similarly, for any $φ\in\mathcal{G}$, we define the Hodge mapping partition function associated to $φ$, prove that it is integrable, and study its role in hamiltonian perturbations of the Riemann--Hopf hierarchy possessing a $τ$-structure. Finally, we establish a generalized Hodge--WK correspondence relating different Hodge mapping partition functions.
format Preprint
id arxiv_https___arxiv_org_abs_2308_03568
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Mapping partition functions
Yang, Di
Zagier, Don
Mathematical Physics
Algebraic Geometry
Exactly Solvable and Integrable Systems
We introduce an infinite group action on partition functions of WK type, meaning of the type of the partition function $Z^{\rm WK}$ in the famous result of Witten and Kontsevich expressing the partition function of $ψ$-class integrals on the compactified moduli space $\overline{\mathcal{M}}_{g,n}$ as a $τ$-function for the Korteweg--de Vries hierarchy. Specifically, the group which acts is the group $\mathcal{G}$ of formal power series of one variable $φ(V)=V+O(V^2)$, with group law given by composition, acting in a suitable way on the infinite tuple of variables of the partition functions. In particular, any $φ\in \mathcal{G}$ sends the Witten--Kontsevich (WK) partition function $Z^{\rm WK}$ to a new partition function $Z^φ$, which we call the WK mapping partition function associated to $φ$. We show that the genus zero part of $\log Z^φ$ is independent of $φ$ and give an explicit recursive description for its higher genus parts (loop equation), and as applications of this obtain relationships of the $ψ$-class integrals to Gaussian Unitary Ensemble and generalized Brézin--Gross--Witten correlators. In a different direction, we use $Z^φ$ to construct a new integrable hierarchy, which we call the WK mapping hierarchy associated to $φ$. We show that this hierarchy is a bihamiltonian perturbation of the Riemann--Hopf hierarchy possessing a $τ$-structure, and prove that it is a universal object for all such perturbations. Similarly, for any $φ\in\mathcal{G}$, we define the Hodge mapping partition function associated to $φ$, prove that it is integrable, and study its role in hamiltonian perturbations of the Riemann--Hopf hierarchy possessing a $τ$-structure. Finally, we establish a generalized Hodge--WK correspondence relating different Hodge mapping partition functions.
title Mapping partition functions
topic Mathematical Physics
Algebraic Geometry
Exactly Solvable and Integrable Systems
url https://arxiv.org/abs/2308.03568