Spectral analysis of $q$-deformed unitary ensembles with the Al-Salam--Carlitz weight

Fuente: arXiv
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Auteurs principaux: Byun, Sung-Soo, Jung, Yeong-Gwang, Oh, Jaeseong
Format: Preprint
Publié: 2025
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author Byun, Sung-Soo
Jung, Yeong-Gwang
Oh, Jaeseong
author_facet Byun, Sung-Soo
Jung, Yeong-Gwang
Oh, Jaeseong
contents We study $q$-deformed random unitary ensembles associated with the weight function of the Al-Salam--Carlitz orthogonal polynomials, indexed by a parameter $a < 0$. In the special case $a = -1$, the model reduces to the $q$-deformed Gaussian unitary ensemble. Employing the Flajolet--Viennot theory together with the combinatorics of matchings, we derive an explicit positive-sum expression for the spectral moments. In the double-scaling regime $q = e^{-λ/N}$, where $N$ denotes the ensemble size and $λ> 0$ is fixed, we derive the first two terms in the large-$N$ expansion of the spectral moments. As a consequence, we obtain a closed-form expression for the limiting spectral density. Notably, this density exhibits two successive phase transitions as $λ$ increases, characterised by a reduction in the number of soft edges from two, to one, and eventually to none. Furthermore, we show that the limiting density coincides with the limiting zero distribution of the Al-Salam--Carlitz orthogonal polynomials under the same scaling.
format Preprint
id arxiv_https___arxiv_org_abs_2507_18042
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Spectral analysis of $q$-deformed unitary ensembles with the Al-Salam--Carlitz weight
Byun, Sung-Soo
Jung, Yeong-Gwang
Oh, Jaeseong
Mathematical Physics
Combinatorics
Probability
We study $q$-deformed random unitary ensembles associated with the weight function of the Al-Salam--Carlitz orthogonal polynomials, indexed by a parameter $a < 0$. In the special case $a = -1$, the model reduces to the $q$-deformed Gaussian unitary ensemble. Employing the Flajolet--Viennot theory together with the combinatorics of matchings, we derive an explicit positive-sum expression for the spectral moments. In the double-scaling regime $q = e^{-λ/N}$, where $N$ denotes the ensemble size and $λ> 0$ is fixed, we derive the first two terms in the large-$N$ expansion of the spectral moments. As a consequence, we obtain a closed-form expression for the limiting spectral density. Notably, this density exhibits two successive phase transitions as $λ$ increases, characterised by a reduction in the number of soft edges from two, to one, and eventually to none. Furthermore, we show that the limiting density coincides with the limiting zero distribution of the Al-Salam--Carlitz orthogonal polynomials under the same scaling.
title Spectral analysis of $q$-deformed unitary ensembles with the Al-Salam--Carlitz weight
topic Mathematical Physics
Combinatorics
Probability
url https://arxiv.org/abs/2507.18042