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Publications (6 of 6) Show all publications
Lambert, G. & Najnudel, J. (2026). Subcritical multiplicative chaos and the characteristic polynomial of the CβE. Probability theory and related fields
Open this publication in new window or tab >>Subcritical multiplicative chaos and the characteristic polynomial of the CβE
2026 (English)In: Probability theory and related fields, ISSN 0178-8051, E-ISSN 1432-2064Article in journal (Refereed) Epub ahead of print
Abstract [en]

The goal of this article is to expand on the relationship between random matrix and multiplicative chaos theories using the integrability properties of the circular β-ensembles. We obtain the multiplicative chaos convergence for the characteristic polynomial and eigenvalue counting function of the circular β-ensembles throughout the subcritical phase, including negative powers. This generalizes recent results in the unitary case, [8, 40], to any β>0 and for the eigenvalue counting field.

Place, publisher, year, edition, pages
Springer Nature, 2026
National Category
Mathematical Analysis
Identifiers
urn:nbn:se:kth:diva-383385 (URN)10.1007/s00440-026-01501-0 (DOI)001778986100001 ()2-s2.0-105040375515 (Scopus ID)
Note

QC 20260611

Available from: 2026-06-11 Created: 2026-06-11 Last updated: 2026-06-11Bibliographically approved
Deleporte, A. & Lambert, G. (2025). Central limit theorem for smooth statistics of one-dimensional free fermions. Journal of the London Mathematical Society, 111(1), Article ID e70045.
Open this publication in new window or tab >>Central limit theorem for smooth statistics of one-dimensional free fermions
2025 (English)In: Journal of the London Mathematical Society, ISSN 0024-6107, E-ISSN 1469-7750, Vol. 111, no 1, article id e70045Article in journal (Refereed) Published
Abstract [en]

We consider the determinantal point processes associated with the spectral projectors of a Schrödinger operator on (Formula presented.), with a smooth confining potential. In the semiclassical limit, where the number of particles tends to infinity, we obtain a Szegő-type central limit theorem for the fluctuations of smooth linear statistics. More precisely, the Laplace transform of any statistic converges without renormalisation to a Gaussian limit with a (Formula presented.) -type variance, which depends on the potential. In the one-well (one-cut) case, using the quantum action-angle theorem and additional micro-local tools, we reduce the problem to the asymptotics of Fredholm determinants of certain approximately Toeplitz operators. In the multi-cut case, we show that for generic potentials, a similar result holds and the contributions of the different wells are independent in the limit.

Place, publisher, year, edition, pages
Wiley, 2025
National Category
Probability Theory and Statistics
Identifiers
urn:nbn:se:kth:diva-358238 (URN)10.1112/jlms.70045 (DOI)001445988500006 ()2-s2.0-85212700386 (Scopus ID)
Note

QC 20250425

Available from: 2025-01-07 Created: 2025-01-07 Last updated: 2025-04-25Bibliographically approved
Deleporte, A. & Lambert, G. (2025). Universality for free fermions and the local Weyl law for semiclassical Schrödinger operators. Journal of the European Mathematical Society (Print), 27(10), 3929-4026
Open this publication in new window or tab >>Universality for free fermions and the local Weyl law for semiclassical Schrödinger operators
2025 (English)In: Journal of the European Mathematical Society (Print), ISSN 1435-9855, E-ISSN 1435-9863, Vol. 27, no 10, p. 3929-4026Article in journal (Refereed) Published
Abstract [en]

We study local asymptotics for the spectral projector associated to a Schrödinger operator ħ2 ∆ + V on Rn in the semiclassical limit as ħ → 0. We prove local uniform convergence of the rescaled integral kernel of this projector towards a universal model, inside the classically allowed region as well as on its boundary. This implies universality of microscopic fluctuations for the corresponding free fermions (determinantal) point processes, both in the bulk and around regular boundary points. Our results apply to a general class of smooth potentials in arbitrary dimension n ≥ 1. These results are complemented by studying both macroscopic and mesoscopic fluctuations of the point process. We obtain tail bounds for macroscopic linear statistics and, provided n ≥ 2, a central limit theorem for both macroscopic and mesoscopic linear statistics in the bulk.

Place, publisher, year, edition, pages
European Mathematical Society - EMS - Publishing House GmbH, 2025
Keywords
determinantal point processes, Schrödinger operators, semiclassical analysis, Weyl law
National Category
Mathematical Analysis
Identifiers
urn:nbn:se:kth:diva-370050 (URN)10.4171/JEMS/1447 (DOI)001543494600001 ()2-s2.0-105012827692 (Scopus ID)
Note

QC 20250925

Available from: 2025-09-25 Created: 2025-09-25 Last updated: 2025-09-25Bibliographically approved
Courteaut, K., Johansson, K. & Lambert, G. (2024). From Berry–Esseen to super-exponential. Electronic Journal of Probability, 29, Article ID 11.
Open this publication in new window or tab >>From Berry–Esseen to super-exponential
2024 (English)In: Electronic Journal of Probability, E-ISSN 1083-6489, Vol. 29, article id 11Article in journal (Refereed) Published
Abstract [en]

For any integer m < n, where m can depend on n, we study the rate of convergence (Formula Presented) to its limiting Gaussian as n → ∞ for orthogonal, unitary and symplectic Haar distributed random matrices U of size n. In the unitary case, we prove that the total variation distance is less than (Formula Presented) times a constant. This result interpolates between the super-exponential bound obtained for fixed m and the 1/n bound coming from the Berry–Esseen theorem applicable when m ≥ n by a result of Rains. We obtain analogous results for the orthogonal and symplectic groups. In these cases, our total variation upper bound takes the form (Formula Presented) times a constant and the result holds provided n > 2m. For m = 1, we obtain complementary lower bounds and precise asymptotics for the L2-distances as n → ∞, which show how sharp our results are.

Place, publisher, year, edition, pages
Institute of Mathematical Statistics, 2024
Keywords
classical compact groups, Haar measure, Hankel determinants, rate of convergence, Toeplitz determinants
National Category
Mathematical Analysis
Identifiers
urn:nbn:se:kth:diva-344004 (URN)10.1214/23-EJP1068 (DOI)001165378300001 ()2-s2.0-85185324572 (Scopus ID)
Note

QC 20240229

Available from: 2024-02-28 Created: 2024-02-28 Last updated: 2025-12-05Bibliographically approved
Junnila, J., Lambert, G. & Webb, C. (2024). Multiplicative chaos measures from thick points of log-correlated fields. Communications on Pure and Applied Mathematics, 77(11), 4212-4286
Open this publication in new window or tab >>Multiplicative chaos measures from thick points of log-correlated fields
2024 (English)In: Communications on Pure and Applied Mathematics, ISSN 0010-3640, E-ISSN 1097-0312, Vol. 77, no 11, p. 4212-4286Article in journal (Refereed) Published
Abstract [en]

We prove that multiplicative chaos measures can be constructed from extreme level sets or thick points of the underlying logarithmically correlated field. We develop a method which covers the whole subcritical phase and only requires asymptotics of suitable exponential moments for the field. As an application, we establish that these estimates hold for the logarithm of the absolute value of the characteristic polynomial of a Haar distributed random unitary matrix (CUE), using known asymptotics for Toeplitz determinant with (merging) Fisher–Hartwig singularities. Hence, this proves a conjecture of Fyodorov and Keating concerning the fluctuations of the volume of thick points of the CUE characteristic polynomial.

Place, publisher, year, edition, pages
Wiley, 2024
National Category
Probability Theory and Statistics Mathematical Analysis
Identifiers
urn:nbn:se:kth:diva-366347 (URN)10.1002/cpa.22205 (DOI)001224523800001 ()2-s2.0-85193366097 (Scopus ID)
Note

QC 20250707

Available from: 2025-07-07 Created: 2025-07-07 Last updated: 2025-08-04Bibliographically approved
Courteaut, K., Johansson, K. & Lambert, G.From Berry-Esseen to super-exponential.
Open this publication in new window or tab >>From Berry-Esseen to super-exponential
(English)Manuscript (preprint) (Other academic)
Abstract [en]

For any integer $m<n$, where $m$ can depend on $n$, we study the rate of convergence of $\frac{1}{\sqrt{m}}\tr \mathbf{U}^m$ to its limiting Gaussian as $n\to\infty$ for orthogonal, unitary and symplectic Haar distributed random matrices $\mathbf{U}$ of size $n$. In the unitary case, we prove that the total variation distance is less than $\Gamma(\floor{n/m}+2)^{-1}m^{-\floor{n/m}}\floor{n/m}^{1/4}\sqrt{\log n}$ times a constant. This result interpolates between the super-exponential bound obtained for fixed $m$ and the $1/n$ bound coming from the Berry-Esseen theorem applicable when $m\ge n$ by a result of Rains. We obtain analogous results for the orthogonal and symplectic groups. In these cases, our total variation upper bound takes the form $\Gamma(2\floor{n/m}+1)^{-1/2}m^{-\floor{n/m}+1}(\log n)^{1/4}$ times a constant and the result holds provided $n \geq 2m$. For $m=1$, we obtain complementary lower bounds and precise asymptotics for the $L^2$-distances as $n\to\infty$, which show how sharp our results are. 

National Category
Probability Theory and Statistics
Identifiers
urn:nbn:se:kth:diva-326109 (URN)
Note

QCR 20230426

Available from: 2023-04-24 Created: 2023-04-24 Last updated: 2023-05-04Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5260-2239

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