{"title":"Multiplicity results for constant Q-curvature conformal metrics","authors":"Salomón Alarcón, Jimmy Petean, Carolina Rey","doi":"10.1007/s00526-024-02762-0","DOIUrl":"https://doi.org/10.1007/s00526-024-02762-0","url":null,"abstract":"<p>In this paper we provide a positive lower bound for the number of metrics of constant <i>Q</i>-curvature which are conformal to a Riemannian product of the form <span>((Mtimes X, g+delta h))</span>, where <span>(delta >0)</span> is a small positive constant, (<i>M</i>, <i>g</i>) is a closed (compact without boundary) <i>n</i>-dimensional Riemannian manifold and (<i>X</i>, <i>h</i>) a closed <i>m</i>-dimensional (positive) Einstein manifold. We assume that <span>(mge 3)</span> and <span>(nge 2)</span> or, if <span>(m=2)</span>, that <span>(nge 7)</span>. More specifically, we study the constant <i>Q</i>-curvature equation on the Riemannian product <span>((Mtimes X, g+delta h))</span>, which becomes, by restricting the equation to functions which depend only on the <i>M</i>-variable, a subcritical equation on (<i>M</i>, <i>g</i>) driven by a fourth order operator, known as the Paneitz operator. Then we prove that, for <span>(delta >0)</span> small enough, the equation has at least <span>(textrm{Cat}(M))</span> positive solutions, where <span>(textrm{Cat}(M))</span> is the Lusternik-Schnirelmann category of <i>M</i>. This implies that there are at least <span>(textrm{Cat}(M))</span> metrics of constant <i>Q</i>-curvature in the conformal class of the Riemannian product <span>((Mtimes X, g+delta h))</span>.</p>","PeriodicalId":9478,"journal":{"name":"Calculus of Variations and Partial Differential Equations","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141515270","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}
{"title":"Existence of singular isoperimetric regions in 8-dimensional manifolds","authors":"Gongping Niu","doi":"10.1007/s00526-024-02748-y","DOIUrl":"https://doi.org/10.1007/s00526-024-02748-y","url":null,"abstract":"<p>It is well known that isoperimetric regions in a smooth compact <span>((n+1))</span>-manifold are themselves smooth, up to a closed set of codimension at most 8. In this note, we construct an 8-dimensional compact smooth manifold whose unique isoperimetric region with half volume that of the manifold exhibits two isolated singularities. This stands in contrast with the situation in which a manifold is a space form, where isoperimetric regions are smooth in every dimension.</p>","PeriodicalId":9478,"journal":{"name":"Calculus of Variations and Partial Differential Equations","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141552101","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}
{"title":"On the critical exponent $$p_c$$ of the 3D quasilinear wave equation $$-big (1+(partial _tphi )^pbig )partial _t^2phi +Delta phi =0$$ with short pulse initial data: II—shock formation","authors":"Lu Yu, Yin Huicheng","doi":"10.1007/s00526-024-02753-1","DOIUrl":"https://doi.org/10.1007/s00526-024-02753-1","url":null,"abstract":"<p>In the previous paper (Ding et al. in J Differ Equ 385:183–253, 2024), for the 3D quasilinear wave equation <span>(-big (1+(partial _tphi )^pbig )partial _t^2phi +Delta phi =0)</span> with short pulse initial data <span>((phi ,partial _tphi )(1,x)=big (delta ^{2-varepsilon _{0}}phi _0 (frac{r-1}{delta },omega ),delta ^{1-varepsilon _{0}}phi _1(frac{r-1}{delta },omega )big ))</span>, where <span>(pin mathbb {N})</span>, <span>(0<varepsilon _{0}<1)</span>, under the outgoing constraint condition <span>((partial _t+partial _r)^kphi (1,x)=O(delta ^{2-varepsilon _{0}-kmax {0,1-(1-varepsilon _{0})p}}))</span> for <span>(k=1,2)</span>, the authors establish the global existence of smooth large solution <span>(phi )</span> when <span>(p>p_c)</span> with <span>(p_c=frac{1}{1-varepsilon _{0}})</span>. In the present paper, under the same outgoing constraint condition, when <span>(1le ple p_c)</span>, we will show that the smooth solution <span>(phi )</span> may blow up and further the outgoing shock is formed in finite time.</p>","PeriodicalId":9478,"journal":{"name":"Calculus of Variations and Partial Differential Equations","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141551999","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}
{"title":"Normalized solutions for a fractional Schrödinger–Poisson system with critical growth","authors":"Xiaoming He, Yuxi Meng, Marco Squassina","doi":"10.1007/s00526-024-02749-x","DOIUrl":"https://doi.org/10.1007/s00526-024-02749-x","url":null,"abstract":"<p>In this paper, we study the fractional critical Schrödinger–Poisson system </p><span>$$begin{aligned}{left{ begin{array}{ll} (-Delta )^su +lambda phi u= alpha u+mu |u|^{q-2}u+|u|^{2^*_s-2}u,&{}~~ hbox {in}~{mathbb {R}}^3, (-Delta )^tphi =u^2,&{}~~ hbox {in}~{mathbb {R}}^3,end{array}right. } end{aligned}$$</span><p>having prescribed mass </p><span>$$begin{aligned} int _{{mathbb {R}}^3} |u|^2dx=a^2,end{aligned}$$</span><p>where <span>( s, t in (0, 1))</span> satisfy <span>(2,s+2t> 3, qin (2,2^*_s), a>0)</span> and <span>(lambda ,mu >0)</span> parameters and <span>(alpha in {mathbb {R}})</span> is an undetermined parameter. For this problem, under the <span>(L^2)</span>-subcritical perturbation <span>(mu |u|^{q-2}u, qin (2,2+frac{4,s}{3}))</span>, we derive the existence of multiple normalized solutions by means of the truncation technique, concentration-compactness principle and the genus theory. In the <span>(L^2)</span>-supercritical perturbation <span>(mu |u|^{q-2}u,qin (2+frac{4,s}{3}, 2^*_s))</span>, we prove two different results of normalized solutions when parameters <span>(lambda ,mu )</span> satisfy different assumptions, by applying the constrained variational methods and the mountain pass theorem. Our results extend and improve some previous ones of Zhang et al. (Adv Nonlinear Stud 16:15–30, 2016); and of Teng (J Differ Equ 261:3061–3106, 2016), since we are concerned with normalized solutions.</p>","PeriodicalId":9478,"journal":{"name":"Calculus of Variations and Partial Differential Equations","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141515271","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}
{"title":"Rigidity of Schouten tensor under conformal deformation","authors":"Mijia Lai, Guoqiang Wu","doi":"10.1007/s00526-024-02751-3","DOIUrl":"https://doi.org/10.1007/s00526-024-02751-3","url":null,"abstract":"<p>We obtain some rigidity results for metrics whose Schouten tensor is bounded from below after conformal transformations. Liang Cheng [5] recently proved that a complete, nonflat, locally conformally flat manifold with Ricci pinching condition (<span>(Ric-epsilon Rgge 0)</span>) must be compact. This answers higher dimensional Hamilton’s pinching conjecture on locally conformally flat manifolds affirmatively. Since (modified) Schouten tensor being nonnegative is equivalent to a Ricci pinching condition, our main result yields a simple proof of Cheng’s theorem.</p>","PeriodicalId":9478,"journal":{"name":"Calculus of Variations and Partial Differential Equations","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141515274","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}
{"title":"Counterexamples to the comparison principle in the special Lagrangian potential equation","authors":"Karl K. Brustad","doi":"10.1007/s00526-024-02747-z","DOIUrl":"https://doi.org/10.1007/s00526-024-02747-z","url":null,"abstract":"<p>For each <span>(k = 0,dots ,n)</span> we construct a continuous <i>phase</i> <span>(f_k)</span>, with <span>(f_k(0) = (n-2k)frac{pi }{2})</span>, and viscosity sub- and supersolutions <span>(v_k)</span>, <span>(u_k)</span>, of the elliptic PDE <span>(sum _{i=1}^n arctan (lambda _i(mathcal {H}w)) = f_k(x))</span> such that <span>(v_k-u_k)</span> has an isolated maximum at the origin. It has been an open question whether the comparison principle would hold in this second order equation for arbitrary continuous phases <span>(f:mathbb {R}^nsupseteq Omega rightarrow (-npi /2,npi /2))</span>. Our examples show it does not.\u0000</p>","PeriodicalId":9478,"journal":{"name":"Calculus of Variations and Partial Differential Equations","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141259746","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}
{"title":"Regularized mean curvature flow for invariant hypersurfaces in a Hilbert space and its application to gauge theory","authors":"Naoyuki Koike","doi":"10.1007/s00526-024-02745-1","DOIUrl":"https://doi.org/10.1007/s00526-024-02745-1","url":null,"abstract":"<p>In this paper, we investigate a regularized mean curvature flow starting from an invariant hypersurface in a Hilbert space equipped with an isometric and almost free action of a Hilbert Lie group whose orbits are minimal regularizable submanifolds. We prove that, if the initial invariant hypersurface satisfies a certain kind of horizontally convexity condition and some additional conditions, then it collapses to an orbit of the Hilbert Lie group action along the regularized mean curvature flow. In the final section, we state a vision for applying the study of the regularized mean curvature flow to the gauge theory.</p>","PeriodicalId":9478,"journal":{"name":"Calculus of Variations and Partial Differential Equations","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141259373","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}
Leilei Cui, Yong Liu, Chunhua Wang, Jun Wang, Wen Yang
{"title":"The Einstein-scalar field Lichnerowicz equations on graphs","authors":"Leilei Cui, Yong Liu, Chunhua Wang, Jun Wang, Wen Yang","doi":"10.1007/s00526-024-02737-1","DOIUrl":"https://doi.org/10.1007/s00526-024-02737-1","url":null,"abstract":"<p>In this article, we consider the Einstein-scalar field Lichnerowicz equation </p><span>$$begin{aligned} -Delta u+hu=Bu^{p-1}+Au^{-p-1} end{aligned}$$</span><p>on any connected finite graph <span>(G=(V,E))</span>, where <i>A</i>, <i>B</i>, <i>h</i> are given functions on <i>V</i> with <span>(Age 0)</span>, <span>(Anot equiv 0)</span> on <i>V</i>, and <span>(p>2)</span> is a constant. By using the classical variational method, topological degree theory and heat-flow method, we provide a systematical study on this equation by providing the existence results for each case: positive, negative and null Yamabe-scalar field conformal invariant, namely <span>(h>0)</span>, <span>(h<0)</span> and <span>(h=0)</span> respectively.</p>","PeriodicalId":9478,"journal":{"name":"Calculus of Variations and Partial Differential Equations","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141259365","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}
{"title":"Normalized solutions to Schrödinger equations in the strongly sublinear regime","authors":"Jarosław Mederski, Jacopo Schino","doi":"10.1007/s00526-024-02729-1","DOIUrl":"https://doi.org/10.1007/s00526-024-02729-1","url":null,"abstract":"<p>We look for solutions to the Schrödinger equation </p><span>$$begin{aligned} -Delta u + lambda u = g(u) quad text {in } mathbb {R}^N end{aligned}$$</span><p>coupled with the mass constraint <span>(int _{mathbb {R}^N}|u|^2,dx = rho ^2)</span>, with <span>(Nge 2)</span>. The behaviour of <i>g</i> at the origin is allowed to be strongly sublinear, i.e., <span>(lim _{srightarrow 0}g(s)/s = -infty )</span>, which includes the case </p><span>$$begin{aligned} g(s) = alpha s ln s^2 + mu |s|^{p-2} s end{aligned}$$</span><p>with <span>(alpha > 0)</span> and <span>(mu in mathbb {R})</span>, <span>(2 < p le 2^*)</span> properly chosen. We consider a family of approximating problems that can be set in <span>(H^1(mathbb {R}^N))</span> and the corresponding least-energy solutions, then we prove that such a family of solutions converges to a least-energy one to the original problem. Additionally, under certain assumptions about <i>g</i> that allow us to work in a suitable subspace of <span>(H^1(mathbb {R}^N))</span>, we prove the existence of infinitely, many solutions.</p>","PeriodicalId":9478,"journal":{"name":"Calculus of Variations and Partial Differential Equations","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141189242","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}
Federico Luigi Dipasquale, Vincent Millot, Adriano Pisante
{"title":"Torus-like solutions for the Landau-de Gennes model. Part III: torus vs split minimizers","authors":"Federico Luigi Dipasquale, Vincent Millot, Adriano Pisante","doi":"10.1007/s00526-024-02743-3","DOIUrl":"https://doi.org/10.1007/s00526-024-02743-3","url":null,"abstract":"<p>We study the behaviour of global minimizers of a continuum Landau–de Gennes energy functional for nematic liquid crystals, in three-dimensional axially symmetric domains diffeomorphic to a ball (a nematic droplet) and in a restricted class of <span>(mathbb {S}^1)</span>-equivariant configurations. It is known from our previous paper (Dipasquale et al. in J Funct Anal 286:110314, 2024) that, assuming smooth and uniaxial (e.g. homeotropic) boundary conditions and a physically relevant norm constraint in the interior (Lyuksyutov constraint), minimizing configurations are either of <i>torus</i> or of <i>split</i> type. Here, starting from a nematic droplet with the homeotropic boundary condition, we show how singular (split) solutions or smooth (torus) solutions (or even both) for the Euler–Lagrange equations do appear as energy minimizers by suitably deforming either the domain or the boundary data. As a consequence, we derive symmetry breaking results for the minimization among all competitors.</p>","PeriodicalId":9478,"journal":{"name":"Calculus of Variations and Partial Differential Equations","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141168451","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}