{"title":"Sesquilinear forms as eigenvectors in quasi *-algebras, with an application to ladder elements","authors":"Fabio Bagarello, Hiroshi Inoue, Salvatore Triolo","doi":"10.1002/mana.202400291","DOIUrl":null,"url":null,"abstract":"<p>We consider a particular class of sesquilinear forms on a Banach quasi *-algebra <span></span><math>\n <semantics>\n <mrow>\n <mrow>\n <mo>(</mo>\n <mi>A</mi>\n <mo>[</mo>\n <mo>∥</mo>\n <mo>.</mo>\n <mo>∥</mo>\n <mo>]</mo>\n <mo>,</mo>\n </mrow>\n <msub>\n <mi>A</mi>\n <mn>0</mn>\n </msub>\n <msub>\n <mrow>\n <mo>[</mo>\n <mo>∥</mo>\n <mo>.</mo>\n <mo>∥</mo>\n </mrow>\n <mn>0</mn>\n </msub>\n <mrow>\n <mo>]</mo>\n <mo>)</mo>\n </mrow>\n </mrow>\n <annotation>$({\\cal A}[\\Vert .\\Vert],{\\cal A}_0[\\Vert .\\Vert _0])$</annotation>\n </semantics></math> that we call <i>eigenstates of an element</i> <span></span><math>\n <semantics>\n <mrow>\n <mi>a</mi>\n <mo>∈</mo>\n <mi>A</mi>\n </mrow>\n <annotation>$a\\in {\\cal A}$</annotation>\n </semantics></math>, and we deduce some of their properties. We further apply our definition to a family of ladder elements, that is, elements of <span></span><math>\n <semantics>\n <mi>A</mi>\n <annotation>${\\cal A}$</annotation>\n </semantics></math> obeying certain commutation relations physically motivated, and we discuss several results, including orthogonality and biorthogonality of the forms, via Gelfand–Naimark–Segal (GNS) representation.</p>","PeriodicalId":49853,"journal":{"name":"Mathematische Nachrichten","volume":"298 3","pages":"1062-1075"},"PeriodicalIF":0.8000,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mana.202400291","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Mathematische Nachrichten","FirstCategoryId":"100","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/mana.202400291","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
Sesquilinear forms as eigenvectors in quasi *-algebras, with an application to ladder elements
We consider a particular class of sesquilinear forms on a Banach quasi *-algebra that we call eigenstates of an element , and we deduce some of their properties. We further apply our definition to a family of ladder elements, that is, elements of obeying certain commutation relations physically motivated, and we discuss several results, including orthogonality and biorthogonality of the forms, via Gelfand–Naimark–Segal (GNS) representation.
期刊介绍:
Mathematische Nachrichten - Mathematical News publishes original papers on new results and methods that hold prospect for substantial progress in mathematics and its applications. All branches of analysis, algebra, number theory, geometry and topology, flow mechanics and theoretical aspects of stochastics are given special emphasis. Mathematische Nachrichten is indexed/abstracted in Current Contents/Physical, Chemical and Earth Sciences; Mathematical Review; Zentralblatt für Mathematik; Math Database on STN International, INSPEC; Science Citation Index