Abstract
We consider a two parameter family of unitarily invariant diffusion processes on the general linear group of invertible matrices, that includes the standard Brownian motion as well as the usual unitary Brownian motion as special cases. We prove that all such processes have Gaussian spectral fluctuations in high dimension with error of order ; this is in terms of the finite dimensional distributions of the process under a large class of test functions known as trace polynomials. We give an explicit characterization of the covariance of the Gaussian fluctuation field, which can be described in terms of a fixed functional of three freely independent free multiplicative Brownian motions. These results generalize earlier work of Lévy and Maïda, and Diaconis and Evans, on unitary groups.
Nous considérons une famille à deux paramètres de processus unitairement invariants sur le groupe général linéaire des matrices inversibles, contenant comme cas particuliers le mouvement brownien standard ainsi que le mouvement brownien unitaire. Nous montrons que tous ces processus ont des fluctuations spectrales gaussiennes d’ordre en grande dimension ; ces fluctuations sont établies pour les distributions finies-dimensionnelles du processus sous une classe étendue de fonctions tests appelées polynômes à trace. Nous donnons une expression explicite de la covariance du champ gaussien des fluctuations en fonction d’une fonctionnelle particulière de trois mouvements browniens multiplicatifs librement indépendants. Ces résultats généralisent les précédents travaux de Lévy et Maïda, et de Diaconis et Evans, sur les groupes unitaires.
Funding Statement
The first author was Supported by the ERC advanced grant “Noncommutative distributions in free probability”. The second author was Supported by NSF CAREER Award DMS-1254807.
Acknowledgements
The authors wish to thank Bruce Driver for several very helpful mathematical conversations during the production of this paper. In particular, we thank him for making us aware of the integral representation of Lemma 3.8, which greatly simplified the exposition of the proof of Theorem 3.3. We also wish to extend our gratitude to the Fields Institute, for its excellent Workshop on Analytic, Stochastic, and Operator Algebraic Aspects of Noncommutative Distributions and Free Probability in July 2013, during which the authors met for the first time and conceived of the core ideas that led to the present work. Finally, we wish to express our thanks to the anonymous referee, who provided very detailed feedback on the paper, especially in Sections 3 and 4, that helped us to significantly improve the exposition.
Citation
Guillaume Cébron. Todd Kemp. "Fluctuations of Brownian motions on ." Ann. Inst. H. Poincaré Probab. Statist. 58 (1) 524 - 547, February 2022. https://doi.org/10.1214/21-AIHP1165
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