Commentarii Mathematici Helvetici最新文献

{"title":"Some analytic aspects of automorphic forms on GL(2) of minimal type","authors":"Yueke Hu, Paul D. Nelson, A. Saha","doi":"10.4171/cmh/473","DOIUrl":"https://doi.org/10.4171/cmh/473","url":null,"abstract":"Let $pi$ be a cuspidal automorphic representation of $PGL_2(mathbb{A}_mathbb{Q})$ of arithmetic conductor $C$ and archimedean parameter $T$, and let $phi$ be an $L^2$-normalized automorphic form in the space of $pi$. The sup-norm problem asks for bounds on $| phi |_infty$ in terms of $C$ and $T$. The quantum unique ergodicity (QUE) problem concerns the limiting behavior of the $L^2$-mass $|phi|^2 (g) , d g$ of $phi$. All previous work on these problems in the conductor-aspect has focused on the case that $phi$ is a newform. \u0000In this work, we study these problems for a class of automorphic forms that are not newforms. Precisely, we assume that for each prime divisor $p$ of $C$, the local component $pi_p$ is supercuspidal (and satisfies some additional technical hypotheses), and consider automorphic forms $phi$ for which the local components $phi_p in pi_p$ are \"minimal\" vectors. Such vectors may be understood as non-archimedean analogues of lowest weight vectors in holomorphic discrete series representations of $PGL_2(mathbb{R})$. \u0000For automorphic forms as above, we prove a sup-norm bound that is sharper than what is known in the newform case. In particular, if $pi_infty$ is a holomorphic discrete series of lowest weight $k$, we obtain the optimal bound $C^{1/8 -epsilon} k^{1/4 - epsilon} ll_{epsilon} |phi|_infty ll_{epsilon} C^{1/8 + epsilon} k^{1/4+epsilon}$. We prove also that these forms give analytic test vectors for the QUE period, thereby demonstrating the equivalence between the strong QUE and the subconvexity problems for this class of vectors. This finding contrasts the known failure of this equivalence for newforms of powerful level.","PeriodicalId":50664,"journal":{"name":"Commentarii Mathematici Helvetici","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2017-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47689082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fourier optimization and prime gaps","authors":"E. Carneiro, M. Milinovich, K. Soundararajan","doi":"10.4171/CMH/467","DOIUrl":"https://doi.org/10.4171/CMH/467","url":null,"abstract":"We investigate some extremal problems in Fourier analysis and their connection to a problem in prime number theory. In particular, we improve the current bounds for the largest possible gap between consecutive primes assuming the Riemann hypothesis.","PeriodicalId":50664,"journal":{"name":"Commentarii Mathematici Helvetici","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2017-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4171/CMH/467","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48439160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On rational cuspidal plane curves and the local cohomology of Jacobian rings","authors":"A. Dimca","doi":"10.4171/cmh/471","DOIUrl":"https://doi.org/10.4171/cmh/471","url":null,"abstract":"This note gives the complete projective classification of rational, cuspidal plane curves of degree at least 6, and having only weighted homogeneous singularities. It also sheds new light on some previous characterizations of free and nearly free curves in terms of Tjurina numbers. Finally, we suggest a stronger form of Terao’s conjecture on the freeness of a line arrangement being determined by its combinatorics.","PeriodicalId":50664,"journal":{"name":"Commentarii Mathematici Helvetici","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2017-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4171/cmh/471","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45348374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Nirenberg problem of prescribed Gauss curvature on $S^2$","authors":"Michael T. Anderson","doi":"10.4171/cmh/512","DOIUrl":"https://doi.org/10.4171/cmh/512","url":null,"abstract":"We introduce a new perspective on the classical Nirenberg problem of understanding the possible Gauss curvatures of metrics on $S^{2}$ conformal to the round metric. A key tool is to employ the smooth Cheeger-Gromov compactness theorem to obtain general a priori estimates for Gauss curvatures $K$ which are in stable orbits of the conformal group $mathrm{Conf}(S^{2})$. We prove that in such a stable region, the map $u rightarrow K_{g}$, $g = e^{2u}g_{+1}$ is a proper Fredholm map with well-defined degree on each component. This leads to a number of new existence and non-existence results. \u0000We also present a new proof and generalization of the Moser theorem on Gauss curvatures of even conformal metrics on $S^{2}$. In contrast to previous work, the work here does not use any of the Sobolev-type inequalities of Trudinger-Moser-Aubin-Onofri.","PeriodicalId":50664,"journal":{"name":"Commentarii Mathematici Helvetici","volume":"21 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2017-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91308426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamically exotic contact spheres in dimensions $geq 7$","authors":"Marcelo R. R. Alves, Matthias Meiwes","doi":"10.4171/cmh/468","DOIUrl":"https://doi.org/10.4171/cmh/468","url":null,"abstract":"We exhibit the first examples of contact structures on $S^{2n-1}$ with $ngeq 4$ and on $S^3times S^2$, all equipped with their standard smooth structures, for which every Reeb flow has positive topological entropy. As a new technical tool for the study of the volume growth of Reeb flows we introduce the notion of algebraic growth of wrapped Floer homology. Its power stems from its stability under several geometric operations on Liouville domains.","PeriodicalId":50664,"journal":{"name":"Commentarii Mathematici Helvetici","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2017-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4171/cmh/468","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43803909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hyperbolic components of rational maps: Quantitative equidistribution and counting","authors":"T. Gauthier, Y. Okuyama, Gabriel Vigny","doi":"10.4171/CMH/462","DOIUrl":"https://doi.org/10.4171/CMH/462","url":null,"abstract":"Let $Lambda$ be a quasi-projective variety and assume that, either $Lambda$ is a subvariety of the moduli space $mathcal{M}_d$ of degree $d$ rational maps, or $Lambda$ parametrizes an algebraic family $(f_lambda)_{lambdainLambda}$ of degree $d$ rational maps on $mathbb{P}^1$. We prove the equidistribution of parameters having $p$ distinct neutral cycles towards the $p$-th bifurcation current letting the periods of the cycles go to $infty$, with an exponential speed of convergence. We deduce several fundamental consequences of this result on equidistribution and counting of hyperbolic components. A key step of the proof is a locally uniform version of the quantitative approximation of the Lyapunov exponent of a rational map by the $log^+$ of the modulus of the multipliers of periodic points.","PeriodicalId":50664,"journal":{"name":"Commentarii Mathematici Helvetici","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2017-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4171/CMH/462","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48372205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Motives of isogenous K3 surfaces","authors":"D. Huybrechts","doi":"10.4171/cmh/465","DOIUrl":"https://doi.org/10.4171/cmh/465","url":null,"abstract":"We prove that isogenous K3 surfaces have isomorphic Chow motives. This provides a motivic interpretation of a long standing conjecture of Safarevich which has been settled only recently by Buskin. The main step consists of a new proof of Safarevich's conjecture that circumvents the analytic parts in Buskin's approach, avoiding twistor spaces and non-algebraic K3 surfaces.","PeriodicalId":50664,"journal":{"name":"Commentarii Mathematici Helvetici","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2017-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4171/cmh/465","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49584930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Complete minimal submanifolds with nullity in Euclidean spheres","authors":"M. Dajczer, Theodoros Kasioumis, A. Savas-Halilaj, T. Vlachos","doi":"10.4171/CMH/446","DOIUrl":"https://doi.org/10.4171/CMH/446","url":null,"abstract":"In this paper we investigate m-dimensional complete minimal submanifolds in Euclidean spheres with index of relative nullity at least m−2 at any point. These are austere submanifolds in the sense of Harvey and Lawson [19] and were initially studied by Bryant [3]. For any dimension and codimension there is an abundance of non-complete examples fully described by Dajczer and Florit [7] in terms of a class of surfaces, called elliptic, for which the ellipse of curvature of a certain order is a circle at any point. Under the assumption of completeness, it turns out that any submanifold is either totally geodesic or has dimension three. In the latter case there are plenty of examples, even compact ones. Under the mild assumption that the Omori-Yau maximum principle holds on the manifold, a trivial condition in the compact case, we provide a complete local parametric description of the submanifolds in terms of 1-isotropic surfaces in Euclidean space. These are the minimal surfaces for which the standard ellipse of curvature is a circle at any point. For these surfaces, there exists a Weierstrass type representation that generates all simply connected ones. Let M be a complete m-dimensional Riemannian manifold. In [10] we considered the case of minimal isometric immersions into Euclidean space f : M → R, m ≥ 3, satisfying that the index of relative nullity is at least m − 2 at any point. Under the mild assumption that the Omori-Yau maximum principle holds on M, we concluded that any f must be “trivial”, namely, just a cylinder over a complete minimal surface. This result is global in nature since for any dimension there are plenty of non-complete examples other than open subsets of cylinders. It is natural to expect rather different type of conclusions when considering a similar global problem for minimal isometric immersions into nonflat space forms. For instance, for submanifolds in the hyperbolic space one would guess that under the same condition on the relative nullity index there exist many non-trivial examples, and that a kind of triviality conclusion will only hold under a strong additional assumption. The third author would like to acknowledge financial support from the grant DFG SM 78/6-1.","PeriodicalId":50664,"journal":{"name":"Commentarii Mathematici Helvetici","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2017-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4171/CMH/446","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49013349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Statistical distribution of the Stern sequence","authors":"S. Bettin, S. Drappeau, Lukas Spiegelhofer","doi":"10.4171/CMH/460","DOIUrl":"https://doi.org/10.4171/CMH/460","url":null,"abstract":"We prove that the Stern diatomic sequence is asymptotically distributed according to a normal law, on a logarithmic scale. This is obtained by studying complex moments, and the analytic properties of a transfer operator.","PeriodicalId":50664,"journal":{"name":"Commentarii Mathematici Helvetici","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2017-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4171/CMH/460","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46311898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The zero norm subspace of bounded cohomology of acylindrically hyperbolic groups","authors":"Federico Franceschini, R. Frigerio, M. B. Pozzetti, A. Sisto","doi":"10.4171/CMH/456","DOIUrl":"https://doi.org/10.4171/CMH/456","url":null,"abstract":"We construct combinatorial volume forms of hyperbolic three manifolds fibering over the circle. These forms define non-trivial classes in bounded cohomology. After introducing a new seminorm on exact bounded cohomology, we use these combinatorial classes to show that, in degree 3, the zero norm subspace of the bounded cohomology of an acylindrically hyperbolic group is infinite dimensional. In the appendix we use the same techniques to give a cohomological proof of a lower bound, originally due to Brock, on the volume of the mapping torus of a cobounded pseudo-Anosov homeomorphism of a closed surface in terms of its Teichm\"uller translation distance.","PeriodicalId":50664,"journal":{"name":"Commentarii Mathematici Helvetici","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2017-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4171/CMH/456","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48725562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}