{"title":"Limit behavior of Weyl coefficients","authors":"R. Pruckner, H. Woracek","doi":"10.1090/spmj/1729","DOIUrl":null,"url":null,"abstract":"<p>The sets of radial or nontangential limit points towards <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"i normal infinity\">\n <mml:semantics>\n <mml:mrow>\n <mml:mi>i</mml:mi>\n <mml:mi mathvariant=\"normal\">∞<!-- ∞ --></mml:mi>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">i\\infty</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> of a Nevanlinna function <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"q\">\n <mml:semantics>\n <mml:mi>q</mml:mi>\n <mml:annotation encoding=\"application/x-tex\">q</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> are studied. Given a nonempty, closed, and connected subset <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"script upper L\">\n <mml:semantics>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mi class=\"MJX-tex-caligraphic\" mathvariant=\"script\">L</mml:mi>\n </mml:mrow>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">{\\mathcal {L}}</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> of <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"double-struck upper C Subscript plus Baseline overbar\">\n <mml:semantics>\n <mml:mover>\n <mml:msub>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mi mathvariant=\"double-struck\">C</mml:mi>\n </mml:mrow>\n </mml:mrow>\n <mml:mo>+</mml:mo>\n </mml:msub>\n <mml:mo accent=\"false\">¯<!-- ¯ --></mml:mo>\n </mml:mover>\n <mml:annotation encoding=\"application/x-tex\">\\overline {{\\mathbb {C}}_+}</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula>, a Hamiltonian <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper H\">\n <mml:semantics>\n <mml:mi>H</mml:mi>\n <mml:annotation encoding=\"application/x-tex\">H</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> is constructed explicitly such that the radial and outer angular cluster sets towards <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"i normal infinity\">\n <mml:semantics>\n <mml:mrow>\n <mml:mi>i</mml:mi>\n <mml:mi mathvariant=\"normal\">∞<!-- ∞ --></mml:mi>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">i\\infty</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> of the Weyl coefficient <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"q Subscript upper H\">\n <mml:semantics>\n <mml:msub>\n <mml:mi>q</mml:mi>\n <mml:mi>H</mml:mi>\n </mml:msub>\n <mml:annotation encoding=\"application/x-tex\">q_H</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> are both equal to <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"script upper L\">\n <mml:semantics>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mi class=\"MJX-tex-caligraphic\" mathvariant=\"script\">L</mml:mi>\n </mml:mrow>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">{\\mathcal {L}}</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula>. The method is based on a study of the continuous group action of rescaling operators on the set of all Hamiltonians.</p>","PeriodicalId":51162,"journal":{"name":"St Petersburg Mathematical Journal","volume":" ","pages":""},"PeriodicalIF":0.7000,"publicationDate":"2022-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"St Petersburg Mathematical Journal","FirstCategoryId":"100","ListUrlMain":"https://doi.org/10.1090/spmj/1729","RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 1
Abstract
The sets of radial or nontangential limit points towards i∞i\infty of a Nevanlinna function qq are studied. Given a nonempty, closed, and connected subset L{\mathcal {L}} of C+¯\overline {{\mathbb {C}}_+}, a Hamiltonian HH is constructed explicitly such that the radial and outer angular cluster sets towards i∞i\infty of the Weyl coefficient qHq_H are both equal to L{\mathcal {L}}. The method is based on a study of the continuous group action of rescaling operators on the set of all Hamiltonians.
期刊介绍:
This journal is a cover-to-cover translation into English of Algebra i Analiz, published six times a year by the mathematics section of the Russian Academy of Sciences.