Central limit theorem for the sine-$β$ point process at $β\le 2$
Sergei M. Gorbunov
TL;DR
The paper proves a Soshnikov-type central limit theorem for the sine-$β$ process in the regime $β\le 2$, by analyzing regularized additive functionals $\overline{S}_f$ with $f$ in the $1/2$-Sobolev class and studying their scaling limit under $f(x/R)$. The authors bridge circular $β$-ensembles and the sine process through Jack polynomial techniques, obtaining a Gessel-type expansion for multiplicative functionals via Jack measures and establishing sharp Laplace-transform bounds that yield Gaussian fluctuations and subgaussian tails. They prove convergence of additive functionals for the circular ensemble with $n$ particles to a Gaussian distribution for all $1/2$-Sobolev regular $f$ when $β\le 2$, and they derive a rate of convergence in Kolmogorov–Smirnov distance of order $(\ln R)^{-1/2}$. A key component is linking expectations of multiplicative functionals to Jack measures, generalizing the Schur-measure/Gessel connection to the Jack setting, and enabling a cohesive framework to translate from finite-$n$ ensembles to the sine limit. The results advance the understanding of fluctuations in $β$-ensembles, provide explicit quantitative bounds, and connect random matrix-type limits with symmetric-function theory through Jack polynomials and measures.
Abstract
The purpose of this paper is to establish the analogue of the Soshnikov Central Limit Theorem for the sine-$β$ process at $β\le 2$. We consider regularized additive functionals, which correspond to 1-Sobolev regular functions $f(x/R)$, in the limit $R\to\infty$. Their convergence to the Gaussian distribution with respect to the Kolmogorov-Smirnov metric at the rate $(\ln R)^{-1/2}$ is established. The proof is based on the convergence of the circular $β$-ensemble to the sine-$β$ process, which was shown by Killip and Stoiciu. We find a convenient bound for the Laplace transforms of additive functionals under the circular $β$-ensemble, which holds under the scaling limit, suggested by Killip and Stoiciu. Further, we show that the additive functionals under the circular $β$-ensemble with $n$ particles converge to the gaussian distribution as $n\to\infty$ for all $1/2$-Sobolev regular functions for $β\le 2$, as was conjectured by Lambert. Finally, in order to prove the limit theorem for the circular $β$-ensemble we derive the connection between expectations of multiplicative functionals and the Jack measures, which generalizes the connection between the circular unitary ensemble and the Schur measures given by Gessel's theorem.
