Pub Date : 2026-01-21DOI: 10.1016/j.jfa.2026.111362
Benedetta Noris , Giovanni Siclari , Gianmaria Verzini
We consider the well-known shape optimization problem with spectral cost: minimizing the first eigenvalue of the Dirichlet Laplacian among all subdomains Ω having prescribed volume and contained in a fixed box D; equivalently, we look for the best way to remove a compact set (obstacle) of Lebesgue measure , , in order to minimize the first Dirichlet eigenvalue of the set .
In the small volume regime , we prove that the optimal obstacles accumulate, in a suitable sense, to points of ∂D where is minimal, where denotes the first eigenfunction of the Dirichlet Laplacian on D. Moreover, we provide a fairly detailed description of the convergence of the optimal eigenvalues, eigenfunctions and free boundaries. Our results are based on sharp estimates of the optimal eigenvalues, in terms of a suitable notion of relative capacity.
{"title":"Miminization of the first eigenvalue of the Dirichlet Laplacian with a small volume obstacle","authors":"Benedetta Noris , Giovanni Siclari , Gianmaria Verzini","doi":"10.1016/j.jfa.2026.111362","DOIUrl":"10.1016/j.jfa.2026.111362","url":null,"abstract":"<div><div>We consider the well-known shape optimization problem with spectral cost: minimizing the first eigenvalue of the Dirichlet Laplacian among all subdomains Ω having prescribed volume and contained in a fixed box <em>D</em>; equivalently, we look for the best way to remove a compact set (obstacle) <span><math><mi>K</mi><mo>⊂</mo><mover><mrow><mi>D</mi></mrow><mo>‾</mo></mover></math></span> of Lebesgue measure <span><math><mo>|</mo><mi>K</mi><mo>|</mo><mo>=</mo><mi>ε</mi></math></span>, <span><math><mn>0</mn><mo><</mo><mi>ε</mi><mo><</mo><mo>|</mo><mi>D</mi><mo>|</mo></math></span>, in order to minimize the first Dirichlet eigenvalue of the set <span><math><mi>Ω</mi><mo>=</mo><mi>D</mi><mo>∖</mo><mi>K</mi></math></span>.</div><div>In the small volume regime <span><math><mi>ε</mi><mo>→</mo><mn>0</mn></math></span>, we prove that the optimal obstacles accumulate, in a suitable sense, to points of ∂<em>D</em> where <span><math><mo>|</mo><mi>∇</mi><msub><mrow><mi>ϕ</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>|</mo></math></span> is minimal, where <span><math><msub><mrow><mi>ϕ</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> denotes the first eigenfunction of the Dirichlet Laplacian on <em>D</em>. Moreover, we provide a fairly detailed description of the convergence of the optimal eigenvalues, eigenfunctions and free boundaries. Our results are based on sharp estimates of the optimal eigenvalues, in terms of a suitable notion of relative capacity.</div></div>","PeriodicalId":15750,"journal":{"name":"Journal of Functional Analysis","volume":"290 8","pages":"Article 111362"},"PeriodicalIF":1.6,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-21DOI: 10.1016/j.jfa.2026.111366
Guofang Wang , Wei Wei , Xuwen Zhang
In this paper, we prove two Liouville-type theorems for capillary minimal graph over . First, if u has linear growth, then for and for any , or and , u must be flat. Second, if u is one-sided bounded on , then for any n and , u must be flat. The proofs build upon gradient estimates for the mean curvature equation over with capillary boundary condition, which are based on carefully adapting the maximum principle to the capillary setting.
{"title":"Half-space Liouville-type theorems for minimal graphs with capillary boundary","authors":"Guofang Wang , Wei Wei , Xuwen Zhang","doi":"10.1016/j.jfa.2026.111366","DOIUrl":"10.1016/j.jfa.2026.111366","url":null,"abstract":"<div><div>In this paper, we prove two Liouville-type theorems for capillary minimal graph over <span><math><msubsup><mrow><mi>R</mi></mrow><mrow><mo>+</mo></mrow><mrow><mi>n</mi></mrow></msubsup></math></span>. First, if <em>u</em> has linear growth, then for <span><math><mi>n</mi><mo>=</mo><mn>2</mn><mo>,</mo><mn>3</mn></math></span> and for any <span><math><mi>θ</mi><mo>∈</mo><mo>(</mo><mn>0</mn><mo>,</mo><mi>π</mi><mo>)</mo></math></span>, or <span><math><mi>n</mi><mo>≥</mo><mn>4</mn></math></span> and <span><math><mi>θ</mi><mo>∈</mo><mo>(</mo><mfrac><mrow><mi>π</mi></mrow><mrow><mn>6</mn></mrow></mfrac><mo>,</mo><mfrac><mrow><mn>5</mn><mi>π</mi></mrow><mrow><mn>6</mn></mrow></mfrac><mo>)</mo></math></span>, <em>u</em> must be flat. Second, if <em>u</em> is one-sided bounded on <span><math><msubsup><mrow><mi>R</mi></mrow><mrow><mo>+</mo></mrow><mrow><mi>n</mi></mrow></msubsup></math></span>, then for any <em>n</em> and <span><math><mi>θ</mi><mo>∈</mo><mo>(</mo><mn>0</mn><mo>,</mo><mi>π</mi><mo>)</mo></math></span>, <em>u</em> must be flat. The proofs build upon gradient estimates for the mean curvature equation over <span><math><msubsup><mrow><mi>R</mi></mrow><mrow><mo>+</mo></mrow><mrow><mi>n</mi></mrow></msubsup></math></span> with capillary boundary condition, which are based on carefully adapting the maximum principle to the capillary setting.</div></div>","PeriodicalId":15750,"journal":{"name":"Journal of Functional Analysis","volume":"290 9","pages":"Article 111366"},"PeriodicalIF":1.6,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-21DOI: 10.1016/j.jfa.2026.111368
Pierre Bizeul
It is well known that if a random vector satisfies a log-Sobolev inequality, all of its marginals have subgaussian tails. In the spirit of the KLS conjecture, we investigate whether this implication can be reversed under a log-concavity assumption. In the general setting, we improve on a result of Bobkov, establishing the best dimension dependent bound on the log-Sobolev constant of subgaussian log-concave measures, and we investigate some special cases.
{"title":"On the log-Sobolev constant of log-concave vectors","authors":"Pierre Bizeul","doi":"10.1016/j.jfa.2026.111368","DOIUrl":"10.1016/j.jfa.2026.111368","url":null,"abstract":"<div><div>It is well known that if a random vector satisfies a log-Sobolev inequality, all of its marginals have subgaussian tails. In the spirit of the KLS conjecture, we investigate whether this implication can be reversed under a log-concavity assumption. In the general setting, we improve on a result of Bobkov, establishing the best dimension dependent bound on the log-Sobolev constant of subgaussian log-concave measures, and we investigate some special cases.</div></div>","PeriodicalId":15750,"journal":{"name":"Journal of Functional Analysis","volume":"290 9","pages":"Article 111368"},"PeriodicalIF":1.6,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-21DOI: 10.1016/j.jfa.2026.111349
Dolapo Oyetunbi, Dilian Yang
The 2-adic ring -algebra is the universal -algebra generated by a unitary and an isometry satisfying certain relations. It contains a canonical copy of the Cuntz algebra . We show that is a maximal -subalgebra of . Furthermore, we examine the structure of the fixed-point algebra under a periodic ⁎-automorphism σ of , which is extended from the flip-flop ⁎-automorphism of . We show that the maximality of in extends to the crossed product in , and to the fixed-point algebra in . As a consequences of our main results, a few open questions concerning are resolved.
二进环C -代数Q2是由满足一定关系的酉和等距生成的全称C -代数。它包含了昆兹代数O2的一个规范副本。我们证明O2是Q2的一个极大C - C -子代数。进一步,我们研究了由O2的触发器式的自同构推广而来的Q2的周期式的 -自同构σ下的不动点代数的结构。我们证明了Q2中O2的极大值可以扩展到Q2中O2的交叉积O2的∑z2,以及Q2中O2的不动代数O2的不动代数。由于我们的主要结果,一些关于Q2的开放问题得到了解决。
{"title":"Maximality and symmetry related to the 2-adic ring C⁎-algebra","authors":"Dolapo Oyetunbi, Dilian Yang","doi":"10.1016/j.jfa.2026.111349","DOIUrl":"10.1016/j.jfa.2026.111349","url":null,"abstract":"<div><div>The 2-adic ring <span><math><msup><mrow><mi>C</mi></mrow><mrow><mo>⁎</mo></mrow></msup></math></span>-algebra <span><math><msub><mrow><mi>Q</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> is the universal <span><math><msup><mrow><mi>C</mi></mrow><mrow><mo>⁎</mo></mrow></msup></math></span>-algebra generated by a unitary and an isometry satisfying certain relations. It contains a canonical copy of the Cuntz algebra <span><math><msub><mrow><mi>O</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>. We show that <span><math><msub><mrow><mi>O</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> is a maximal <span><math><msup><mrow><mi>C</mi></mrow><mrow><mo>⁎</mo></mrow></msup></math></span>-subalgebra of <span><math><msub><mrow><mi>Q</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>. Furthermore, we examine the structure of the fixed-point algebra under a periodic <sup>⁎</sup>-automorphism <em>σ</em> of <span><math><msub><mrow><mi>Q</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, which is extended from the flip-flop <sup>⁎</sup>-automorphism of <span><math><msub><mrow><mi>O</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>. We show that the maximality of <span><math><msub><mrow><mi>O</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> in <span><math><msub><mrow><mi>Q</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> extends to the crossed product <span><math><msub><mrow><mi>O</mi></mrow><mrow><mn>2</mn></mrow></msub><msub><mrow><mo>⋊</mo></mrow><mrow><mi>σ</mi></mrow></msub><msub><mrow><mi>Z</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> in <span><math><msub><mrow><mi>Q</mi></mrow><mrow><mn>2</mn></mrow></msub><msub><mrow><mo>⋊</mo></mrow><mrow><mi>σ</mi></mrow></msub><msub><mrow><mi>Z</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, and to the fixed-point algebra <span><math><msubsup><mrow><mi>O</mi></mrow><mrow><mn>2</mn></mrow><mrow><mi>σ</mi></mrow></msubsup></math></span> in <span><math><msubsup><mrow><mi>Q</mi></mrow><mrow><mn>2</mn></mrow><mrow><mi>σ</mi></mrow></msubsup></math></span>. As a consequences of our main results, a few open questions concerning <span><math><msub><mrow><mi>Q</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> are resolved.</div></div>","PeriodicalId":15750,"journal":{"name":"Journal of Functional Analysis","volume":"290 8","pages":"Article 111349"},"PeriodicalIF":1.6,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-14DOI: 10.1016/j.jfa.2026.111345
Ethan Sussman
Recent work by Hintz–Vasy provides a partial asymptotic analysis of the low-energy limit of scattering for Schrödinger operators with a short-range potential. Using a slight refinement of Hintz's algorithm, we complete the asymptotic analysis by providing full asymptotic expansions in every possible asymptotic regime. Moreover, the analysis is done in any dimension , for any asymptotically conic manifold, and we keep track of partial multipole expansions. Applications include full asymptotic analyses of the Schrödinger, wave, and Klein–Gordon equations, one of these being described in a companion paper. Using previous work, only partial asymptotic analyses were possible.
{"title":"Complete asymptotic analysis of low energy scattering for Schrödinger operators with a short-range potential","authors":"Ethan Sussman","doi":"10.1016/j.jfa.2026.111345","DOIUrl":"10.1016/j.jfa.2026.111345","url":null,"abstract":"<div><div>Recent work by Hintz–Vasy provides a partial asymptotic analysis of the low-energy limit of scattering for Schrödinger operators with a short-range potential. Using a slight refinement of Hintz's algorithm, we complete the asymptotic analysis by providing full asymptotic expansions in every possible asymptotic regime. Moreover, the analysis is done in any dimension <span><math><mi>d</mi><mo>≥</mo><mn>3</mn></math></span>, for any asymptotically conic manifold, and we keep track of partial multipole expansions. Applications include full asymptotic analyses of the Schrödinger, wave, and Klein–Gordon equations, one of these being described in a companion paper. Using previous work, only partial asymptotic analyses were possible.</div></div>","PeriodicalId":15750,"journal":{"name":"Journal of Functional Analysis","volume":"290 8","pages":"Article 111345"},"PeriodicalIF":1.6,"publicationDate":"2026-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146036483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-13DOI: 10.1016/j.jfa.2026.111352
Kazuhiro Ishige , Tatsuki Kawakami , Ryo Takada
We study the existence of solutions to the fractional semilinear heat equation with a singular inhomogeneous term. For this aim, we establish decay estimates of the fractional heat semigroup in several uniformly local Zygumnd spaces. Furthermore, we apply the real interpolation method in uniformly local Zygmund spaces to obtain sharp integral estimates on the inhomogeneous term and the nonlinear term. This enables us to find sharp sufficient conditions for the existence of solutions to the fractional semilinear heat equation with a singular inhomogeneous term.
{"title":"Existence of solutions to the fractional semilinear heat equation with a singular inhomogeneous term","authors":"Kazuhiro Ishige , Tatsuki Kawakami , Ryo Takada","doi":"10.1016/j.jfa.2026.111352","DOIUrl":"10.1016/j.jfa.2026.111352","url":null,"abstract":"<div><div>We study the existence of solutions to the fractional semilinear heat equation with a singular inhomogeneous term. For this aim, we establish decay estimates of the fractional heat semigroup in several uniformly local Zygumnd spaces. Furthermore, we apply the real interpolation method in uniformly local Zygmund spaces to obtain sharp integral estimates on the inhomogeneous term and the nonlinear term. This enables us to find sharp sufficient conditions for the existence of solutions to the fractional semilinear heat equation with a singular inhomogeneous term.</div></div>","PeriodicalId":15750,"journal":{"name":"Journal of Functional Analysis","volume":"290 8","pages":"Article 111352"},"PeriodicalIF":1.6,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146036480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-13DOI: 10.1016/j.jfa.2026.111356
Qionglei Chen , Xiaonan Hao , Omar Lazar
We prove a global well-posedness result for a liquid crystal system with bounded but arbitrarily large density and velocity. Applying the Lagrangian approach with more refined estimates we are able to not only work in the critical regularity space but also to overcome the difficulty arising from the fact that we are dealing with a coupled hyperbolic system. Taking advantage of our uniqueness result, we study the density patches problem by using classical techniques, namely, Littlewood-Paley multipliers together with the smoothing effect of the Newtonian potential and on certain symmetry property motivated by [13]. One of the key point of the proof is to introduce the material derivative and perform more refined estimates for the direction field.
{"title":"Global well-posedness and density patches for liquid crystal system","authors":"Qionglei Chen , Xiaonan Hao , Omar Lazar","doi":"10.1016/j.jfa.2026.111356","DOIUrl":"10.1016/j.jfa.2026.111356","url":null,"abstract":"<div><div>We prove a global well-posedness result for a liquid crystal system with bounded but arbitrarily large density and velocity. Applying the Lagrangian approach with more refined estimates we are able to not only work in the critical regularity space but also to overcome the difficulty arising from the fact that we are dealing with a coupled hyperbolic system. Taking advantage of our uniqueness result, we study the density patches problem by using classical techniques, namely, Littlewood-Paley multipliers together with the smoothing effect of the Newtonian potential and on certain symmetry property motivated by <span><span>[13]</span></span>. One of the key point of the proof is to introduce the material derivative and perform more refined estimates for the direction field.</div></div>","PeriodicalId":15750,"journal":{"name":"Journal of Functional Analysis","volume":"290 8","pages":"Article 111356"},"PeriodicalIF":1.6,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146036486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-13DOI: 10.1016/j.jfa.2026.111358
Zhiyuan Yang
We study a generalization of free Poisson random measure by replacing the intensity measure with a n.s.f. weight φ on a von Neumann algebra M. We give an explicit construction of the free Poisson random weight using full Fock space over the Hilbert space and study the free Poisson von Neumann algebra generated by this random weight. This construction can be viewed as a free Poisson type functor for left Hilbert algebras similar to Voiculescu's free Gaussian functor for Hilbert spaces. When , we show that can be decomposed into free product of other algebras. For a general weight φ, we prove that is a factor if and only if and . The second quantization of subunital weight decreasing completely positive maps is studied. By considering a degenerate version of left Hilbert algebras, we are also able to treat free Araki-Woods algebras as special cases of free Poisson algebras for degenerate left Hilbert algebras. We show that the Lévy-Itô decomposition of a jointly freely infinitely divisible family (in a tracial probability space) can in fact be interpreted as a decomposition of a degenerate left Hilbert algebra. Finally, as an application, we give a realization of any additive time-parameterized free Lévy process as unbounded operators in a full Fock space. Using this realization, we show that the filtration algebras of any additive free Lévy process are always interpolated group factors with a possible additional atom.
{"title":"On von Neumann algebras generated by free Poisson random weights","authors":"Zhiyuan Yang","doi":"10.1016/j.jfa.2026.111358","DOIUrl":"10.1016/j.jfa.2026.111358","url":null,"abstract":"<div><div>We study a generalization of free Poisson random measure by replacing the intensity measure with a n.s.f. weight <em>φ</em> on a von Neumann algebra <em>M</em>. We give an explicit construction of the free Poisson random weight using full Fock space over the Hilbert space <span><math><msup><mrow><mi>L</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>(</mo><mi>M</mi><mo>,</mo><mi>φ</mi><mo>)</mo></math></span> and study the free Poisson von Neumann algebra <span><math><mi>Γ</mi><mo>(</mo><mi>M</mi><mo>,</mo><mi>φ</mi><mo>)</mo></math></span> generated by this random weight. This construction can be viewed as a free Poisson type functor for left Hilbert algebras similar to Voiculescu's free Gaussian functor for Hilbert spaces. When <span><math><mi>φ</mi><mo>(</mo><mn>1</mn><mo>)</mo><mo><</mo><mo>∞</mo></math></span>, we show that <span><math><mi>Γ</mi><mo>(</mo><mi>M</mi><mo>,</mo><mi>φ</mi><mo>)</mo></math></span> can be decomposed into free product of other algebras. For a general weight <em>φ</em>, we prove that <span><math><mi>Γ</mi><mo>(</mo><mi>M</mi><mo>,</mo><mi>φ</mi><mo>)</mo></math></span> is a factor if and only if <span><math><mi>φ</mi><mo>(</mo><mn>1</mn><mo>)</mo><mo>≥</mo><mn>1</mn></math></span> and <span><math><mi>M</mi><mo>≠</mo><mi>C</mi></math></span>. The second quantization of subunital weight decreasing completely positive maps is studied. By considering a degenerate version of left Hilbert algebras, we are also able to treat free Araki-Woods algebras as special cases of free Poisson algebras for degenerate left Hilbert algebras. We show that the Lévy-Itô decomposition of a jointly freely infinitely divisible family (in a tracial probability space) can in fact be interpreted as a decomposition of a degenerate left Hilbert algebra. Finally, as an application, we give a realization of any additive time-parameterized free Lévy process as unbounded operators in a full Fock space. Using this realization, we show that the filtration algebras of any additive free Lévy process are always interpolated group factors with a possible additional atom.</div></div>","PeriodicalId":15750,"journal":{"name":"Journal of Functional Analysis","volume":"290 8","pages":"Article 111358"},"PeriodicalIF":1.6,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145969417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-13DOI: 10.1016/j.jfa.2026.111357
Toan T. Nguyen
In this paper, we establish the large time asymptotic behavior of solutions to the linearized Vlasov-Poisson system near general spatially homogeneous equilibria with connected support on the torus or on the whole space , including those that are non-monotone. The problem can be solved completely mode by mode for each spatial wave number, and their longtime dynamics is intimately tied to the “survival threshold” of wave numbers computed by where ϒ is the maximal speed of particle velocities. It is shown that purely oscillatory electric fields exist and obey a Klein-Gordon's type dispersion relation for wave numbers below and up to the threshold, thus rigorously confirming the existence of Langmuir's oscillatory waves for a non-trivial range of spatial frequencies in this linearized setting. At the threshold, the phase velocity of these oscillatory waves enters the range of admissible particle velocities, namely there are particles that move at the same propagation speed of the waves. It is this exact resonant interaction between particles and the oscillatory fields that causes the waves to be damped, classically known as Landau damping. Landau's law of decay is explicitly computed and is sensitive to the decaying rate of the background equilibria. The faster it decays at the maximal velocity, the weaker Landau damping is. Beyond the threshold, the electric fields are a perturbation of those generated by the free transport dynamics and thus decay rapidly fast due to the phase mixing mechanism.
{"title":"Landau damping and survival threshold","authors":"Toan T. Nguyen","doi":"10.1016/j.jfa.2026.111357","DOIUrl":"10.1016/j.jfa.2026.111357","url":null,"abstract":"<div><div>In this paper, we establish the large time asymptotic behavior of solutions to the linearized Vlasov-Poisson system near general spatially homogeneous equilibria <span><math><mi>μ</mi><mo>(</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac><mo>|</mo><mi>v</mi><msup><mrow><mo>|</mo></mrow><mrow><mn>2</mn></mrow></msup><mo>)</mo></math></span> with connected support on the torus <span><math><msubsup><mrow><mi>T</mi></mrow><mrow><mi>x</mi></mrow><mrow><mn>3</mn></mrow></msubsup><mo>×</mo><msubsup><mrow><mi>R</mi></mrow><mrow><mi>v</mi></mrow><mrow><mn>3</mn></mrow></msubsup></math></span> or on the whole space <span><math><msubsup><mrow><mi>R</mi></mrow><mrow><mi>x</mi></mrow><mrow><mn>3</mn></mrow></msubsup><mo>×</mo><msubsup><mrow><mi>R</mi></mrow><mrow><mi>v</mi></mrow><mrow><mn>3</mn></mrow></msubsup></math></span>, including those that are non-monotone. The problem can be solved completely mode by mode for each spatial wave number, and their longtime dynamics is intimately tied to the “survival threshold” of wave numbers computed by<span><span><span><math><msubsup><mrow><mi>κ</mi></mrow><mrow><mn>0</mn></mrow><mrow><mn>2</mn></mrow></msubsup><mo>=</mo><mn>4</mn><mi>π</mi><munderover><mo>∫</mo><mrow><mn>0</mn></mrow><mrow><mi>ϒ</mi></mrow></munderover><mfrac><mrow><msup><mrow><mi>u</mi></mrow><mrow><mn>2</mn></mrow></msup><mi>μ</mi><mo>(</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac><msup><mrow><mi>u</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>)</mo></mrow><mrow><msup><mrow><mi>ϒ</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>−</mo><msup><mrow><mi>u</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></mfrac><mspace></mspace><mi>d</mi><mi>u</mi></math></span></span></span> where ϒ is the maximal speed of particle velocities. It is shown that purely oscillatory electric fields exist and obey a Klein-Gordon's type dispersion relation for wave numbers below and up to the threshold, thus rigorously confirming the existence of Langmuir's oscillatory waves for a non-trivial range of spatial frequencies in this linearized setting. At the threshold, the phase velocity of these oscillatory waves enters the range of admissible particle velocities, namely there are particles that move at the same propagation speed of the waves. It is this exact resonant interaction between particles and the oscillatory fields that causes the waves to be damped, classically known as Landau damping. Landau's law of decay is explicitly computed and is sensitive to the decaying rate of the background equilibria. The faster it decays at the maximal velocity, the weaker Landau damping is. Beyond the threshold, the electric fields are a perturbation of those generated by the free transport dynamics and thus decay rapidly fast due to the phase mixing mechanism.</div></div>","PeriodicalId":15750,"journal":{"name":"Journal of Functional Analysis","volume":"290 8","pages":"Article 111357"},"PeriodicalIF":1.6,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146036481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-13DOI: 10.1016/j.jfa.2026.111351
Adimurthi, Prosenjit Roy, Vivek Sahu
We establish generalized fractional boundary Hardy-type inequality, in the spirit of Caffarelli-Kohn-Nirenberg inequality for different values of s and p on various domains in . In particular, for Lipschitz bounded domains any values of s and p are admissible, settling all the cases in subcritical, supercritical and critical regime. In this paper we have solved the open problems posed by Dyda for the critical case . Moreover we have proved the embeddings of in subcritical, critical and supercritical uniformly without using Dyda's decomposition. Additionally, we extend our results to include a weighted fractional boundary Hardy-type inequality for the critical case.
{"title":"Fractional boundary Hardy inequality for the critical cases","authors":"Adimurthi, Prosenjit Roy, Vivek Sahu","doi":"10.1016/j.jfa.2026.111351","DOIUrl":"10.1016/j.jfa.2026.111351","url":null,"abstract":"<div><div>We establish generalized fractional boundary Hardy-type inequality, in the spirit of Caffarelli-Kohn-Nirenberg inequality for different values of <em>s</em> and <em>p</em> on various domains in <span><math><msup><mrow><mi>R</mi></mrow><mrow><mi>d</mi></mrow></msup><mo>,</mo><mspace></mspace><mi>d</mi><mo>≥</mo><mn>1</mn></math></span>. In particular, for Lipschitz bounded domains any values of <em>s</em> and <em>p</em> are admissible, settling all the cases in subcritical, supercritical and critical regime. In this paper we have solved the open problems posed by Dyda for the critical case <span><math><mi>s</mi><mi>p</mi><mo>=</mo><mn>1</mn></math></span>. Moreover we have proved the embeddings of <span><math><msubsup><mrow><mi>W</mi></mrow><mrow><mn>0</mn></mrow><mrow><mi>s</mi><mo>,</mo><mi>p</mi></mrow></msubsup><mo>(</mo><mi>Ω</mi><mo>)</mo></math></span> in subcritical, critical and supercritical uniformly without using Dyda's decomposition. Additionally, we extend our results to include a weighted fractional boundary Hardy-type inequality for the critical case.</div></div>","PeriodicalId":15750,"journal":{"name":"Journal of Functional Analysis","volume":"290 8","pages":"Article 111351"},"PeriodicalIF":1.6,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146036482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}