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Charlier, C. & Lenells, J. (2025). Balayage of Measures: Behavior Near a Cusp. Potential Analysis
Open this publication in new window or tab >>Balayage of Measures: Behavior Near a Cusp
2025 (English)In: Potential Analysis, ISSN 0926-2601, E-ISSN 1572-929XArticle in journal (Refereed) Published
Abstract [en]

Let mu be a positive measure supported on a planar domain Omega. We consider the behavior of the balayage measure v := Bal(mu, partial derivative Omega) near a point z(0) is an element of partial derivative Omega at which Omega has an outward- pointing cusp. Assuming that the order and coefficient of tangency of the cusp are d > 0 and a > 0, respectively, and that d mu (z) asymptotic to|z- z(0)|(2b-2)d(2)z as z -> z(0) for some b > 0 (here d(2)z is the Lebesgue measure on C), we obtain the leading order term of v near z(0). This leading term is universal in the sense that it only depends on d, a, and b. We also treat the case when the domain has multiple corners and cusps at the same point. Finally, we obtain an explicit expression for the balayage of the uniform measure on the tacnodal region between two osculating circles, and we give an application of this result to two-dimensional Coulomb gases.

Place, publisher, year, edition, pages
Springer Nature, 2025
Keywords
Balayage measure, Cusp, Harmonic measure, Boundary behavior, Tacnode, Coulomb gas
National Category
Mathematical Analysis
Identifiers
urn:nbn:se:kth:diva-362969 (URN)10.1007/s11118-025-10212-5 (DOI)001457034100001 ()2-s2.0-105001636549 (Scopus ID)
Note

QC 20250430

Available from: 2025-04-30 Created: 2025-04-30 Last updated: 2025-04-30Bibliographically approved
Charlier, C. & Lenells, J. (2025). Boussinesq's equation for water waves: the soliton resolution conjecture for Sector IV. Advanced Nonlinear Studies, 25(1), 106-151
Open this publication in new window or tab >>Boussinesq's equation for water waves: the soliton resolution conjecture for Sector IV
2025 (English)In: Advanced Nonlinear Studies, ISSN 1536-1365, E-ISSN 2169-0375, Vol. 25, no 1, p. 106-151Article in journal (Refereed) Published
Abstract [en]

We consider the Boussinesq equation on the line for a broad class of Schwartz initial data relevant for water waves. In a recent work, we identified ten main sectors describing the asymptotic behavior of the solution, and for each of these sectors we gave an exact expression for the leading asymptotic term in the case when no solitons are present. In this paper, we derive an asymptotic formula in Sector IV, characterized by xt ∈ (√13, 1), in the case when solitons are present. In particular, our results provide an exact expression for the soliton-radiation interaction to leading order and a verification of the soliton resolution conjecture for the Boussinesq equation in Sector IV.

Place, publisher, year, edition, pages
Walter de Gruyter GmbH, 2025
Keywords
Boussinesq equation, long-time asymptotics, Riemann-Hilbert problem
National Category
Mathematical Analysis
Identifiers
urn:nbn:se:kth:diva-363126 (URN)10.1515/ans-2023-0154 (DOI)001388155000001 ()2-s2.0-105003027260 (Scopus ID)
Note

QC 20250507

Available from: 2025-05-06 Created: 2025-05-06 Last updated: 2025-05-07Bibliographically approved
Berntson, B. K., Langmann, E. & Lenells, J. (2025). Conformal Field Theory, Solitons, and Elliptic Calogero-Sutherland Models. Communications in Mathematical Physics, 406(2), Article ID 33.
Open this publication in new window or tab >>Conformal Field Theory, Solitons, and Elliptic Calogero-Sutherland Models
2025 (English)In: Communications in Mathematical Physics, ISSN 0010-3616, E-ISSN 1432-0916, Vol. 406, no 2, article id 33Article in journal (Refereed) Published
Abstract [en]

We construct a non-chiral conformal field theory (CFT) on the torus that accommodates a second quantization of the elliptic Calogero-Sutherland (eCS) model. We show that the CFT operator that provides this second quantization defines, at the same time, a quantum version of a soliton equation called the non-chiral intermediate long-wave (ncILW) equation. We also show that this CFT operator is a second quantization of a generalized eCS model which can describe arbitrary numbers of four different kinds of particles; we propose that these particles can be identified with solitons of the quantum ncILW equation.

Place, publisher, year, edition, pages
Springer Nature, 2025
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-359506 (URN)10.1007/s00220-024-05188-z (DOI)001396244700001 ()39807298 (PubMedID)2-s2.0-85217482840 (Scopus ID)
Note

QC 20250226

Available from: 2025-02-05 Created: 2025-02-05 Last updated: 2025-02-26Bibliographically approved
Lenells, J. & Roussillon, J. (2025). Semiclassical limit of a non-polynomial q-Askey scheme. Journal of Mathematical Analysis and Applications, 549(1), Article ID 129474.
Open this publication in new window or tab >>Semiclassical limit of a non-polynomial q-Askey scheme
2025 (English)In: Journal of Mathematical Analysis and Applications, ISSN 0022-247X, E-ISSN 1096-0813, Vol. 549, no 1, article id 129474Article in journal (Refereed) Published
Abstract [en]

We prove a semiclassical asymptotic formula for the two elements M and Q lying at the bottom of the recently constructed non-polynomial hyperbolic q-Askey scheme. We also prove that the corresponding exponent is a generating function of the canonical transformation between pairs of Darboux coordinates on the monodromy manifold of the Painlevé I and III3 equations, respectively. Such pairs of coordinates characterize the asymptotics of the tau function of the corresponding Painlevé equation. We conjecture that the other members of the non-polynomial hyperbolic q-Askey scheme yield generating functions associated to the other Painlevé equations in the semiclassical limit.

Place, publisher, year, edition, pages
Elsevier BV, 2025
Keywords
Generating function, Painlevé equation, q-Askey scheme, Semiclassical limit
National Category
Mathematical Analysis
Identifiers
urn:nbn:se:kth:diva-361793 (URN)10.1016/j.jmaa.2025.129474 (DOI)001446171900001 ()2-s2.0-86000521708 (Scopus ID)
Note

QC 20250328

Available from: 2025-03-27 Created: 2025-03-27 Last updated: 2025-03-28Bibliographically approved
Boutet de Monvel, A., Lenells, J. & Shepelsky, D. (2025). The focusing NLS equation with step-like oscillating background: Asymptotics in a transition zone. Journal of Differential Equations, 429, 747-801
Open this publication in new window or tab >>The focusing NLS equation with step-like oscillating background: Asymptotics in a transition zone
2025 (English)In: Journal of Differential Equations, ISSN 0022-0396, E-ISSN 1090-2732, Vol. 429, p. 747-801Article in journal (Refereed) Published
Abstract [en]

In a recent paper, we presented scenarios of long-time asymptotics for the solution of the focusing nonlinear Schrödinger equation with initial data approaching plane waves of the form A1eiϕ1e−2iB1x and A2eiϕ2e−2iB2x at minus and plus infinity, respectively. In the shock case B1<B2 some scenarios include sectors of genus 3, that is, sectors ξ1<ξ<ξ2, ξ≔x/t, where the leading term of the asymptotics is expressed in terms of hyperelliptic functions attached to a Riemann surface of genus 3. The present paper deals with the asymptotic analysis in a transition zone between two genus 3 sectors. The leading term is expressed in terms of elliptic functions attached to a Riemann surface of genus 1. A central step in the derivation is the construction of a local parametrix in a neighborhood of two merging branch points.

Place, publisher, year, edition, pages
Elsevier BV, 2025
National Category
Mathematical Analysis Probability Theory and Statistics
Identifiers
urn:nbn:se:kth:diva-361176 (URN)10.1016/j.jde.2025.02.016 (DOI)001436932500001 ()2-s2.0-85218908149 (Scopus ID)
Note

QC 20250324

Available from: 2025-03-12 Created: 2025-03-12 Last updated: 2025-03-24Bibliographically approved
Langmann, E. & Lenells, J. (2025). Universality of Mean-Field Antiferromagnetic Order in an Anisotropic 3D Hubbard Model at Half-Filling. Journal of statistical physics, 192(1), Article ID 10.
Open this publication in new window or tab >>Universality of Mean-Field Antiferromagnetic Order in an Anisotropic 3D Hubbard Model at Half-Filling
2025 (English)In: Journal of statistical physics, ISSN 0022-4715, E-ISSN 1572-9613, Vol. 192, no 1, article id 10Article in journal (Refereed) Published
Abstract [en]

We study Hartree-Fock theory at half-filling for the 3D anisotropic Hubbard model on a cubic lattice with hopping parameter t in the x- and y-directions and a possibly different hopping parameter t(z) in the z-direction; this model interpolates between the 2D and 3D Hubbard models corresponding to the limiting cases t(z )= 0 and t(z )= t, respectively. We first derive all-order asymptotic expansions for the density of states. Using these expansions and units such that t = 1, we analyze how the Neel temperature and the antiferromagnetic mean field depend on the coupling parameter, U, and on the hopping parameter t(z). We derive asymptotic formulas valid in the weak coupling regime, and we study in particular the transition from the three-dimensional to the two-dimensional model as t(z )-> 0. It is found that the asymptotic formulas are qualitatively different for t(z )= 0 (the two-dimensional case) and t(z )> 0 (the case of nonzero hopping in the z-direction). Our results show that certain universality features of the three-dimensional Hubbard model are lost in the limit t(z )-> 0 in which the three-dimensional model reduces to the two-dimensional model.

Place, publisher, year, edition, pages
Springer Nature, 2025
Keywords
Hubbard model, Hartree-Fock theory, Universality, N & eacute, el temperature, Antiferromagnetism, Mean-field equation
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-359505 (URN)10.1007/s10955-024-03390-w (DOI)001397845500005 ()
Note

QC 20250204

Available from: 2025-02-04 Created: 2025-02-04 Last updated: 2025-02-04Bibliographically approved
Forsström, M. P., Lenells, J. & Viklund, F. (2025). Wilson lines in the lattice Higgs model at strong coupling. The Annals of Applied Probability, 35(1), 590-634
Open this publication in new window or tab >>Wilson lines in the lattice Higgs model at strong coupling
2025 (English)In: The Annals of Applied Probability, ISSN 1050-5164, E-ISSN 2168-8737, Vol. 35, no 1, p. 590-634Article in journal (Refereed) Published
Abstract [en]

We consider the 4D fixed length lattice Higgs model with Wilson action for the gauge field and structure group Zn. We study Wilson line observables in the strong coupling regime and compute their asymptotic behavior with error estimates. Our analysis is based on a high-temperature representation of the lattice Higgs measure combined with Poisson approximation. We also give a short proof of the folklore result that Wilson line (and loop) expectations exhibit perimeter law decay whenever the Higgs field coupling constant is positive.

Place, publisher, year, edition, pages
Institute of Mathematical Statistics, 2025
Keywords
Lattice gauge theory, Wilson lines, Wilson loops, high temperature expansion
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-361277 (URN)10.1214/24-AAP2122 (DOI)001434322900015 ()2-s2.0-105000763640 (Scopus ID)
Note

QC 20250317

Available from: 2025-03-17 Created: 2025-03-17 Last updated: 2025-04-03Bibliographically approved
Charlier, C. & Lenells, J. (2024). Boussinesq's equation for water waves: Asymptotics in Sector I. Advances in Nonlinear Analysis, 13(1), Article ID 20240022.
Open this publication in new window or tab >>Boussinesq's equation for water waves: Asymptotics in Sector I
2024 (English)In: Advances in Nonlinear Analysis, ISSN 2191-9496, Vol. 13, no 1, article id 20240022Article in journal (Refereed) Published
Abstract [en]

In a recent study, we showed that the large ( x , t ) \left(x,t) behavior of a class of physically relevant solutions of Boussinesq's equation for water waves is described by ten main asymptotic sectors. In the sector adjacent to the positive x x -axis, referred to as Sector I, we stated without proof an exact expression for the leading asymptotic term together with an error estimate. Here, we provide a proof of this asymptotic formula.

Place, publisher, year, edition, pages
Walter de Gruyter GmbH, 2024
Keywords
asymptotics, Boussinesq equation, Riemann-Hilbert problem, initial value problem
National Category
Mathematical Analysis
Identifiers
urn:nbn:se:kth:diva-350112 (URN)10.1515/anona-2024-0022 (DOI)001253434300001 ()2-s2.0-85198451295 (Scopus ID)
Note

QC 20240708

Available from: 2024-07-08 Created: 2024-07-08 Last updated: 2024-07-24Bibliographically approved
Charlier, C. & Lenells, J. (2024). Boussinesq’s Equation for Water Waves: Asymptotics in Sector V. SIAM Journal on Mathematical Analysis, 56(3)
Open this publication in new window or tab >>Boussinesq’s Equation for Water Waves: Asymptotics in Sector V
2024 (English)In: SIAM Journal on Mathematical Analysis, ISSN 0036-1410, E-ISSN 1095-7154, Vol. 56, no 3Article in journal (Refereed) Published
Abstract [en]

We consider the Boussinesq equation on the line for a broad class of Schwartz initialdata for which (i) no solitons are present, (ii) the spectral functions have generic behavior near\pm 1,and (iii) the solution exists globally. In a recent work, we identified 10 main sectors describing theasymptotic behavior of the solution, and for each of these sectors we gave an exact expression for theleading asymptotic term. In this paper, we give a proof for the formula corresponding to the sectorxt\in (0,1\surd 3)

Place, publisher, year, edition, pages
Society for Industrial & Applied Mathematics (SIAM), 2024
Keywords
Boussinesq equation, long-time asymptotics, Riemann--Hilbert problem
National Category
Mathematical Analysis
Identifiers
urn:nbn:se:kth:diva-350116 (URN)10.1137/23M1587671 (DOI)001248211500007 ()2-s2.0-85190821361 (Scopus ID)
Note

QC 20240708

Available from: 2024-07-08 Created: 2024-07-08 Last updated: 2024-07-08Bibliographically approved
Ameur, Y., Charlier, C., Cronvall, J. & Lenells, J. (2024). Disk counting statistics near hard edges of random normal matrices: The multi-component regime. Advances in Mathematics, 441, Article ID 109549.
Open this publication in new window or tab >>Disk counting statistics near hard edges of random normal matrices: The multi-component regime
2024 (English)In: Advances in Mathematics, ISSN 0001-8708, E-ISSN 1090-2082, Vol. 441, article id 109549Article in journal (Refereed) Published
Abstract [en]

We consider a two-dimensional point process whose points are separated into two disjoint components by a hard wall, and study the multivariate moment generating function of the corresponding disk counting statistics. We investigate the “hard edge regime” where all disk boundaries are a distance of order [Formula presented] away from the hard wall, where n is the number of points. We prove that as n→+∞, the asymptotics of the moment generating function are of the form [Formula presented] and we determine the constants C1,…,C4 explicitly. The oscillatory term Fn is of order 1 and is given in terms of the Jacobi theta function. Our theorem allows us to derive various precise results on the disk counting function. For example, we prove that the asymptotic fluctuations of the number of points in one component are of order 1 and are given by an oscillatory discrete Gaussian. Furthermore, the variance of this random variable enjoys asymptotics described by the Weierstrass ℘-function.

Place, publisher, year, edition, pages
Elsevier BV, 2024
Keywords
Moment generating functions, Oscillatory asymptotics, Random matrix theory
National Category
Probability Theory and Statistics
Identifiers
urn:nbn:se:kth:diva-344191 (URN)10.1016/j.aim.2024.109549 (DOI)001197414300001 ()2-s2.0-85186094553 (Scopus ID)
Note

QC 20240307

Available from: 2024-03-06 Created: 2024-03-06 Last updated: 2024-04-12Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6191-7769

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