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Hurwitz numbers count branched covers of the Riemann sphere with specified ramification, or equivalently, transitive permutation factorizations in the symmetric group with specified cycle types. Monotone Hurwitz numbers count a restricted…

Combinatorics · Mathematics 2012-10-15 I. P. Goulden , Mathieu Guay-Paquet , Jonathan Novak

In their recent inspiring paper Mironov and Morozov claim a surprisingly simple expansion formula for the Kontsevich-Witten tau-function in terms of the Schur Q-functions. Here we provide a similar conjecture for the Br\'ezin-Gross-Witten…

Mathematical Physics · Physics 2021-01-18 Alexander Alexandrov

Partition functions often become \tau-functions of integrable hierarchies, if they are considered dependent on infinite sets of parameters called time variables. The Hurwitz partition functions Z = \sum_R…

High Energy Physics - Theory · Physics 2015-05-27 A. Alexandrov , A. Mironov , A. Morozov , S. Natanzon

The Hurwitz space is a compactification of the space of rational functions of a given degree. We study the intersection of various strata of this space with its boundary. A study of the cohomology ring of the Hurwitz space then allows us to…

Algebraic Geometry · Mathematics 2007-05-23 Dimitri Zvonkine

The partition function for unitary two matrix models is known to be a double KP tau-function, as well as providing solutions to the two dimensional Toda hierarchy. It is shown how it may also be viewed as a Borel sum regularization of…

Exactly Solvable and Integrable Systems · Physics 2023-08-02 J. Harnad , A. Yu. Orlov

We introduce a single tau function that represents the CKP hierarchy into a generalized Hirota "bilinear" equation. The actions on the tau function by additional symmetries for the hierarchy are calculated, which involve strictly more than…

Exactly Solvable and Integrable Systems · Physics 2015-06-11 Liang Chang , Chao-Zhong Wu

We derive an algorithm to produce explicit formulas for certain generating functions of double Hurwitz numbers. These formulas generalize a formula of Goulden, Jackson and Vakil for one part double Hurwitz numbers. Immediate consequences…

Combinatorics · Mathematics 2010-08-20 Paul Johnson

In this paper, we investigated four applications of the gauge transformation for the BKP hierarchy. Firstly, it is found that the orbit of the gauge transformation for the constrained BKP hierarchy defines a special $(2 +1)$-dimensional…

Exactly Solvable and Integrable Systems · Physics 2013-02-26 Jipeng Cheng , Jingsong He

Hurwitz numbers are the Laurent coefficients of an elliptic function $\wp(u)$ of cyclotomic type, and they are natural generalization of the Bernoulli numbers. This paper gives new generalization of Bernoulli and Hurwitz numbers for higher…

Number Theory · Mathematics 2007-05-23 Yoshihiro Ônishi

We consider multiple sums and multi-integrals as tau functions of the BKP hierarchy using neutral fermions as the simplest tool for deriving these. The sums are over projective Schur functions $Q_\alpha$ for strict partitions $\alpha$. We…

Mathematical Physics · Physics 2018-06-26 J. Harnad , J. W. van de Leur , A. Yu. Orlov

Hurwitz numbers enumerate ramified coverings of the Riemann sphere with fixed ramification data. Certain kinds of ramification data are of particular interest, such as double Hurwitz numbers, which count covers with fixed arbitrary…

Combinatorics · Mathematics 2018-10-09 Marvin Anas Hahn

The KP hierarchy is a completely integrable system of quadratic, partial differential equations that generalizes the KdV hierarchy. A linear combination of Schur functions is a solution to the KP hierarchy if and only if its coefficients…

Combinatorics · Mathematics 2008-03-28 I. P. Goulden , D. M. Jackson

In this paper we continue the study of the double ramification hierarchy of [Bur15]. After showing that the DR hierarchy satisfies tau-symmetry we define its partition function as the (logarithm of the) tau-function of the string solution…

Mathematical Physics · Physics 2018-12-19 A. Buryak , B. Dubrovin , J. Guéré , P. Rossi

We derive the spectral curves for $q$-part double Hurwitz numbers, $r$-spin simple Hurwitz numbers, and arbitrary combinations of these cases, from the analysis of the unstable (0,1)-geometry. We quantize this family of spectral curves and…

Algebraic Geometry · Mathematics 2024-06-26 Motohico Mulase , Sergey Shadrin , Loek Spitz

The discrete KP hierarchy is also known as the $(l-l')$--th modified KP hierarchy. Here in this paper, we consider the corresponding two--component generalization, called the two--component discrete KP (2dKP) hierarchy. Firstly, starting…

Exactly Solvable and Integrable Systems · Physics 2025-08-12 Wenqi Cao , Jipeng Cheng , Jinbiao Wang

In this letter,we present our conjecture on the connection between the Kontsevich--Witten and the Hurwitz tau-functions. The conjectural formula connects these two tau-functions by means of the $GL(\infty)$ group element. An important…

High Energy Physics - Theory · Physics 2013-09-03 A. Alexandrov

Correlation function of twist operators is a natural quantity of interest in two-dimensional conformal field theory (2d CFT) and finds relevance in various physical contexts. For computing twist operator correlators associated with generic…

High Energy Physics - Theory · Physics 2023-07-10 Hewei Frederic Jia

This is a summary of a recursive construction of solutions of the hbar-dependent KP hierarchy. We give recursion relations for the coefficients X_n of an hbar-expansion of the operator X = X_0 + \hbar X_1 + \hbar^2 X_2 + ... for which the…

Mathematical Physics · Physics 2012-06-12 Kanehisa Takasaki , Takashi Takebe

We find all polynomial tau-functions of the n-th reduced BKP hierarchy (=n-th Sawada-Kotera hierarchy). The name comes from the fact that for n=3 the simplest equation of the hierarchy is the famous Sawada-Kotera equation.

Exactly Solvable and Integrable Systems · Physics 2024-02-14 Victor Kac , Johan Van de Leur

We study the series expansion of the tau function of the BKP hierarchy applying the addition formulae of the BKP hierarchy. Any formal power series can be expanded in terms of Schur functions. It is known that, under the condition…

Exactly Solvable and Integrable Systems · Physics 2016-06-22 Yoko Shigyo