Annals of PdePub Date : 2026-10-13DOI: 10.1007/s40818-026-00256-0
Ning Tang
{"title":"Stability of the Catenoid for the Hyperbolic Vanishing Mean Curvature Equation in 4 Spatial Dimensions","authors":"Ning Tang","doi":"10.1007/s40818-026-00256-0","DOIUrl":"10.1007/s40818-026-00256-0","url":null,"abstract":"<div><p>We establish the asymptotic stability of the catenoid, as a nonflat stationary solution to the hyperbolic vanishing mean curvature (HVMC) equation in Minkowski space <img> for <span>(n = 4)</span>. Our main result is under a “codimension-1” assumption on initial perturbation, modulo suitable translation and boost (i.e. modulation), without any symmetry assumptions. In comparison to the <span>(n ge 5)</span> case addressed by Lührmann–Oh–Shahshahani [40], proving catenoid stability in 4 dimensions shares additional difficulties with its 3 dimensional analog, namely the slower spatial decay of the catenoid and slower temporal decay of waves. To overcome these difficulties in the <span>(n = 3)</span> case, the strong Huygens principle, as well as a miraculous cancellation in the source term, plays an important role in [50] to obtain strong late time tails. In <span>(n = 4)</span> dimensions, without these special structural advantages, our novelty is to introduce an appropriate commutator vector field to derive a new hierarchy of estimates with higher <span>(r^p)</span>-weights so that an improved pointwise decay can be established. We expect this to be applicable for proving improved late time tails of other quasilinear wave equations in even dimensions or wave equations with inverse square potential.</p></div>","PeriodicalId":36382,"journal":{"name":"Annals of Pde","volume":"12 2","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s40818-026-00256-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149189014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Annals of PdePub Date : 2026-10-09DOI: 10.1007/s40818-026-00255-1
Víctor Navarro-Fernández, David Villringer
{"title":"Spectral Instability in the Smooth Ponomarenko Dynamo","authors":"Víctor Navarro-Fernández, David Villringer","doi":"10.1007/s40818-026-00255-1","DOIUrl":"10.1007/s40818-026-00255-1","url":null,"abstract":"<div><p>We consider the kinematic dynamo equations for a passive vector in <span>(mathcal {M} times mathbb {T} subseteq mathbb {R}^2 times mathbb {T})</span> describing the evolution of a magnetic field with resistivity <span>(varepsilon > 0)</span>, that is transported by a given velocity field. For a broad class of <span>(C^3)</span> velocity fields with helical geometry, we establish the existence of solutions that exhibit exponential growth over time. We construct an unstable eigenmode via detailed resolvent estimates of the corresponding linear operator, which we carry out by introducing suitable Green’s functions that accurately approximate the local behaviour of the true system. This approach yields an explicit asymptotic expression for the growing mode, providing a sharp description of the instability mechanism. We first derive the results with <span>(mathcal {M}=mathbb {R}^2)</span> for a large class of velocity fields that includes finite energy examples. We then consider the case of domains with boundary, where <span>(mathcal {M}times mathbb {T})</span> denotes a periodic cylinder, annular cylinder, or the exterior of a cylinder, with the boundary conditions of perfectly conducting walls. Our results offer a rigorous and sharp mathematical justification for the physically conjectured process by which helical flows can sustain magnetic field generation in the Ponomarenko dynamo, with growth rate of order <span>(varepsilon ^{1/3})</span>.</p></div>","PeriodicalId":36382,"journal":{"name":"Annals of Pde","volume":"12 2","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s40818-026-00255-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149132770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Annals of PdePub Date : 2026-10-09DOI: 10.1007/s40818-026-00250-6
Hongjing Huang, Mihaela Ifrim, Daniel Tataru
{"title":"Enhanced Lifespan Bounds for 1D Quasilinear Klein–Gordon Flows","authors":"Hongjing Huang, Mihaela Ifrim, Daniel Tataru","doi":"10.1007/s40818-026-00250-6","DOIUrl":"10.1007/s40818-026-00250-6","url":null,"abstract":"<div><p>In this article we consider one-dimensional scalar quasilinear Klein–Gordon equations with general nonlinearities, on both <span>({mathbb {R}})</span> and <span>({mathbb {T}})</span>. By employing a refined modified-energy framework of Ifrim and Tataru, we investigate long time lifespan bounds for small data solutions. Our main result asserts that solutions with small initial data of size <span>(epsilon )</span> persist on the improved cubic timescale <span>(|t| lesssim epsilon ^{-2})</span> and satisfy sharp cubic energy estimates throughout this interval. We also establish difference bounds on the same time scale. In the case of <span>({mathbb {R}})</span>, we are further able to use dispersion in order to extend the lifespan to <span>(epsilon ^{-4})</span>. This generalizes earlier results obtained by Delort [8] in the semilinear case.</p></div>","PeriodicalId":36382,"journal":{"name":"Annals of Pde","volume":"12 2","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s40818-026-00250-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149132771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Annals of PdePub Date : 2026-10-07DOI: 10.1007/s40818-026-00259-x
Sergiu Klainerman, Xuecheng Wang
{"title":"Decay Estimates of Wave Equations in Un-isotropic Media","authors":"Sergiu Klainerman, Xuecheng Wang","doi":"10.1007/s40818-026-00259-x","DOIUrl":"10.1007/s40818-026-00259-x","url":null,"abstract":"<div><p>We prove decay estimates for solutions to non-isotropic linear systems of wave equations in 3<i>D</i>, relevant to wave propagation through uniaxial crystals. The defining feature of these estimates is that they depend only on the commutation properties of the system with the scaling vector field. In the first part of the paper we rely on these commutation properties together with energy estimates and a degenerate Böchner type identity to derive a robust physical space weighted <span>(L^2)</span> to <span>(L^infty )</span> decay estimate. In the second part of the paper we derive sharper <span>(L^1)</span> to <span>(L^infty )</span> decay estimates by the classical method of stationary phase. We demonstrate the power of the method, with surprisingly simple one-page proofs for two new results on small data global regularity for some simplified models of non-isotropic systems of wave equations in <span>({mathbb {R}}^{1+3})</span> with cubic nonlinearities, which include the physical model of nonlinear crystal optics with the Kerr nonlinearity, see [21].</p></div>","PeriodicalId":36382,"journal":{"name":"Annals of Pde","volume":"12 2","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149132176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Annals of PdePub Date : 2026-10-05DOI: 10.1007/s40818-026-00249-z
Rirong Yuan
{"title":"Fully Non-linear Elliptic Equations on Complex Manifolds","authors":"Rirong Yuan","doi":"10.1007/s40818-026-00249-z","DOIUrl":"10.1007/s40818-026-00249-z","url":null,"abstract":"<div><p>In this paper, we study a broad class of fully nonlinear elliptic equations on Hermitian manifolds. On the one hand, under the optimal structural assumptions we derive <span>(C^{2,alpha })</span>-estimates for solutions of the equations on closed Hermitian manifolds. On the other hand, we treat the Dirichlet problem. In both cases, we prove the existence theorems under the unboundedness condition.</p></div>","PeriodicalId":36382,"journal":{"name":"Annals of Pde","volume":"12 2","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149132037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Annals of PdePub Date : 2026-10-01DOI: 10.1007/s40818-026-00257-z
Zexing Li, Tao Zhou
{"title":"Nonradial Stability of Self-Similar Blowup to the Keller–Segel Equation in Three Dimensions","authors":"Zexing Li, Tao Zhou","doi":"10.1007/s40818-026-00257-z","DOIUrl":"10.1007/s40818-026-00257-z","url":null,"abstract":"<div><p>In three dimensions, the parabolic-elliptic Keller-Segel system exhibits a rich variety of singularity formations. Notably, it admits an explicit self-similar blow-up solution whose radial stability, conjectured more than two decades ago in [5], was recently confirmed by Glogić and Schörkhuber [28]. This paper aims to extend the radial stability to the nonradial setting, building on the finite-codimensional stability analysis in our previous work [40]. The main input is the nonradial mode stability of the associated linearized operator. Its inevitable nonlocality, absent in the radial setting, presents essential difficulties for the spectral analysis. Besides a quantitative perturbative analysis for the high spherical classes, we adapt in the first spherical class the wave operator method of Li-Wei-Zhang [35] for the fluid stability to localize the operator and remove the known unstable mode simultaneously. Our method provides localization beyond the partial mass variable and is independent of the explicit formula of the profile, so it potentially sheds light on other linear nonlocal problems.</p></div>","PeriodicalId":36382,"journal":{"name":"Annals of Pde","volume":"12 2","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149132326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Annals of PdePub Date : 2026-09-26DOI: 10.1007/s40818-026-00254-2
Hyungjun Choi
{"title":"Asymmetric Self-Similar Spiral Solutions of 2-D Incompressible Euler Equations","authors":"Hyungjun Choi","doi":"10.1007/s40818-026-00254-2","DOIUrl":"10.1007/s40818-026-00254-2","url":null,"abstract":"<div><p>We construct nonradial, self-similar solutions to the two-dimensional incompressible Euler equations without assuming rotational symmetry. These solutions extend the study of self-similar algebraic spiral flows, initiated by Elling and further developed by Shao–Wei–Zhang [41], where <i>m</i>-fold symmetry with <span>(m ge 2)</span> was assumed. Moreover, they bear resemblance to the numerical simulations of Bressan–Shen [10], in connection with the ongoing investigation into non-uniqueness of solutions.</p></div>","PeriodicalId":36382,"journal":{"name":"Annals of Pde","volume":"12 2","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149133019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Annals of PdePub Date : 2026-09-05DOI: 10.1007/s40818-026-00253-3
Ugo Gianazza, Naian Liao, José Miguel Urbano
{"title":"Improved Moduli of Continuity for Degenerate Phase Transitions","authors":"Ugo Gianazza, Naian Liao, José Miguel Urbano","doi":"10.1007/s40818-026-00253-3","DOIUrl":"10.1007/s40818-026-00253-3","url":null,"abstract":"<div><p>We substantially improve in two scenarios the current state-of-the-art modulus of continuity for weak solutions to the <span>(N-)</span>dimensional, two-phase Stefan problem featuring a <span>(p-)</span>degenerate diffusion: for <span>(p=Nge 3)</span>, we sharpen it to </p><div><div><span>$$ varvec{omega }(r) approx exp (-c| ln r|^{frac{1}{N}}); $$</span></div></div><p>for <span>(p>max {2,N})</span>, we derive an unexpected Hölder modulus.</p></div>","PeriodicalId":36382,"journal":{"name":"Annals of Pde","volume":"12 2","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13546340/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148901138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Annals of PdePub Date : 2026-08-21DOI: 10.1007/s40818-026-00251-5
Michał Kowalczyk, Yvan Martel
{"title":"Asymptotic Analysis of Small Energy Breathers for the Nonlinear Klein–Gordon Equation","authors":"Michał Kowalczyk, Yvan Martel","doi":"10.1007/s40818-026-00251-5","DOIUrl":"10.1007/s40818-026-00251-5","url":null,"abstract":"<div><p>For a general class of nonlinear Klein–Gordon equations, we prove that in the small energy limit, any sequence of breathers decomposes into a finite sum of decoupled, periodically modulated canonical solitons. Each of these solitons is asymptotically equal to an explicit sine-Gordon breather and the distance between them grows to infinity as the energy decreases to 0. Finally we prove that none of these breathers is centered in a bounded set provided that a certain non resonance condition holds.</p></div>","PeriodicalId":36382,"journal":{"name":"Annals of Pde","volume":"12 2","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148782865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Annals of PdePub Date : 2026-08-05DOI: 10.1007/s40818-026-00238-2
Igor Kukavica, Wojciech Ożański
{"title":"Exact Boundary Controllability of the 3D and 2D Incompressible Ideal MHD System","authors":"Igor Kukavica, Wojciech Ożański","doi":"10.1007/s40818-026-00238-2","DOIUrl":"10.1007/s40818-026-00238-2","url":null,"abstract":"<div><p>We consider the three-dimensional ideal MHD system on a domain <span>(Omega ' subset mathbb {R}^3)</span> with an open subset <span>(Gamma )</span> of the boundary <span>(partial Omega ')</span> where we prescribe both <span>(ucdot textsf{n})</span> and <span>(bcdot textsf{n})</span>, while <span>(ucdot textsf{n}= bcdot textsf{n}=0)</span> on <span>(partial Omega ' setminus Gamma )</span>. We prove boundary controllability of the system, namely that we can prescribe the boundary data such that the unique solution of the system with an initial state <span>((u_0,b_0))</span> achieves another state <span>((u_1,b_1))</span> in a finite time, where <span>(u_0,b_0,u_1,b_1)</span> are arbitrary divergence-free vector fields satisfying impermeability boundary condition and which are extendible to vector fields with the same properties on any bounded domain obtained by extension of <span>(Omega ')</span> via <span>(Gamma )</span>. As a byproduct, we give the first local well-posedness proof for the incompressible ideal MHD system which does not use Elsasser variables and is thus applicable to any bounded domain with sufficient Sobolev regularity. We also provide a new, simpler control for the two-dimensional ideal MHD system.</p></div>","PeriodicalId":36382,"journal":{"name":"Annals of Pde","volume":"12 2","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148750919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}