Macdonald Polynomials of Type $C_n$ with One-Column Diagrams and Deformed Catalan Numbers

TL;DR

This paper derives explicit formulas and recursion relations for transition matrices involving Macdonald and Koornwinder polynomials of type $C_n$, revealing connections to deformed Catalan numbers and $q$-ballot numbers.

Contribution

It provides new explicit formulas and recursion relations for transition matrices between specialized Macdonald polynomials and monomial symmetric polynomials of type $C_n$, linking them to deformed Catalan and ballot numbers.

Findings

Explicit formula for transition matrix $\\mathcal{C}$ with one-column diagrams.

Recursion relations deforming Catalan triangle or ballot numbers.

Identification of $q$-ballot numbers as Kostka polynomials in specific cases.

Abstract

We present an explicit formula for the transition matrix $\mathcal{C}$ from the type $C_n$ degeneration of the Koornwinder polynomials $P_{(1^r)}(x\,|\,a,-a,c,-c\,|\,q,t)$ with one column diagrams, to the type $C_n$ monomial symmetric polynomials $m_{(1^{r})}(x)$. The entries of the matrix $\mathcal{C}$ enjoy a set of three term recursion relations, which can be regarded as a $(a,c,t)$-deformation of the one for the Catalan triangle or ballot numbers. Some transition matrices are studied associated with the type $(C_n,C_n)$ Macdonald polynomials $P^{(C_n,C_n)}_{(1^r)}(x\,|\,b;q,t)= P_{(1^r)}\big(x\,|\,b^{1/2},-b^{1/2},q^{1/2}b^{1/2},-q^{1/2}b^{1/2}\,|\,q,t\big)$. It is also shown that the $q$-ballot numbers appear as the Kostka polynomials, namely in the transition matrix from the Schur polynomials $P^{(C_n,C_n)}_{(1^r)}(x\,|\,q;q,q)$ to the Hall-Littlewood polynomials $P^{(C_n,C_n)}_{(1^r)}(x\,|\,t;0,t)$.