Free energy expansion of determinantal Coulomb gases in the quadratic fields with a point charge

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Main Authors: Byun, Sung-Soo, Yang, Meng, Yoo, Eui
Format: Preprint
Published: 2026
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author Byun, Sung-Soo
Yang, Meng
Yoo, Eui
author_facet Byun, Sung-Soo
Yang, Meng
Yoo, Eui
contents We study a determinantal Coulomb gas in the complex plane associated with the external potential $$ Q(z)=\frac{1}{1-τ^2}\big(|z|^2-τ\text{Re } z^2\big)-2c\log|z-a|, $$ where $τ\in[0,1)$, $c\ge0$, and $a\ge0$. In the regimes where the associated droplet is simply or doubly connected, we derive the free energy expansion up to and including the constant term, with all coefficients computed explicitly, thereby extending recent results in the isotropic case $τ=0$. In particular, we identify the constant term with the Liouville action associated with the droplet. Our result admits a natural interpretation in terms of asymptotic expansions of moments of characteristic polynomials for the elliptic Ginibre ensemble. The proof is based on a deformation framework involving both the singularity location $a$ and the anisotropy parameter $τ$, relating variations of the free energy to refined asymptotics of planar orthogonal polynomials. The asymptotic analysis relies on the foliation flow method of Hedenmalm and Wennman, providing an alternative to the Riemann--Hilbert approach used in the isotropic setting. The present work suggests a general framework connecting free energy expansions, refined asymptotics of planar orthogonal polynomials, and conformally invariant geometric functionals, with several intermediate results already formulated for general algebraic Hele-Shaw potentials.
format Preprint
id arxiv_https___arxiv_org_abs_2605_29594
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Free energy expansion of determinantal Coulomb gases in the quadratic fields with a point charge
Byun, Sung-Soo
Yang, Meng
Yoo, Eui
Mathematical Physics
Complex Variables
Probability
We study a determinantal Coulomb gas in the complex plane associated with the external potential $$ Q(z)=\frac{1}{1-τ^2}\big(|z|^2-τ\text{Re } z^2\big)-2c\log|z-a|, $$ where $τ\in[0,1)$, $c\ge0$, and $a\ge0$. In the regimes where the associated droplet is simply or doubly connected, we derive the free energy expansion up to and including the constant term, with all coefficients computed explicitly, thereby extending recent results in the isotropic case $τ=0$. In particular, we identify the constant term with the Liouville action associated with the droplet. Our result admits a natural interpretation in terms of asymptotic expansions of moments of characteristic polynomials for the elliptic Ginibre ensemble. The proof is based on a deformation framework involving both the singularity location $a$ and the anisotropy parameter $τ$, relating variations of the free energy to refined asymptotics of planar orthogonal polynomials. The asymptotic analysis relies on the foliation flow method of Hedenmalm and Wennman, providing an alternative to the Riemann--Hilbert approach used in the isotropic setting. The present work suggests a general framework connecting free energy expansions, refined asymptotics of planar orthogonal polynomials, and conformally invariant geometric functionals, with several intermediate results already formulated for general algebraic Hele-Shaw potentials.
title Free energy expansion of determinantal Coulomb gases in the quadratic fields with a point charge
topic Mathematical Physics
Complex Variables
Probability
url https://arxiv.org/abs/2605.29594