{"title":"正态变种上主束的对数连接","authors":"Jyoti Dasgupta , Bivas Khan , Mainak Poddar","doi":"10.1016/j.bulsci.2025.103715","DOIUrl":null,"url":null,"abstract":"<div><div>Let <em>X</em> be a normal projective variety over an algebraically closed field of characteristic zero. Let <em>D</em> be a reduced Weil divisor on <em>X</em>. Let <em>G</em> be a reductive linear algebraic group. We study logarithmic connections on a principal <em>G</em>-bundle over <em>X</em>, which are singular along <em>D</em>. We give necessary and sufficient conditions for the existence of such a connection in terms of connections on associated vector bundles when the logarithmic tangent sheaf of <em>X</em> is locally free. The existence of a logarithmic connection on a principal bundle over a projective toric variety, singular along the boundary divisor, is shown to be equivalent to the existence of a torus equivariant structure on the bundle.</div></div>","PeriodicalId":55313,"journal":{"name":"Bulletin des Sciences Mathematiques","volume":"206 ","pages":"Article 103715"},"PeriodicalIF":0.9000,"publicationDate":"2025-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Logarithmic connections on principal bundles over normal varieties\",\"authors\":\"Jyoti Dasgupta , Bivas Khan , Mainak Poddar\",\"doi\":\"10.1016/j.bulsci.2025.103715\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>Let <em>X</em> be a normal projective variety over an algebraically closed field of characteristic zero. Let <em>D</em> be a reduced Weil divisor on <em>X</em>. Let <em>G</em> be a reductive linear algebraic group. We study logarithmic connections on a principal <em>G</em>-bundle over <em>X</em>, which are singular along <em>D</em>. We give necessary and sufficient conditions for the existence of such a connection in terms of connections on associated vector bundles when the logarithmic tangent sheaf of <em>X</em> is locally free. The existence of a logarithmic connection on a principal bundle over a projective toric variety, singular along the boundary divisor, is shown to be equivalent to the existence of a torus equivariant structure on the bundle.</div></div>\",\"PeriodicalId\":55313,\"journal\":{\"name\":\"Bulletin des Sciences Mathematiques\",\"volume\":\"206 \",\"pages\":\"Article 103715\"},\"PeriodicalIF\":0.9000,\"publicationDate\":\"2025-08-29\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Bulletin des Sciences Mathematiques\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0007449725001411\",\"RegionNum\":3,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"MATHEMATICS, APPLIED\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Bulletin des Sciences Mathematiques","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0007449725001411","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS, APPLIED","Score":null,"Total":0}
Logarithmic connections on principal bundles over normal varieties
Let X be a normal projective variety over an algebraically closed field of characteristic zero. Let D be a reduced Weil divisor on X. Let G be a reductive linear algebraic group. We study logarithmic connections on a principal G-bundle over X, which are singular along D. We give necessary and sufficient conditions for the existence of such a connection in terms of connections on associated vector bundles when the logarithmic tangent sheaf of X is locally free. The existence of a logarithmic connection on a principal bundle over a projective toric variety, singular along the boundary divisor, is shown to be equivalent to the existence of a torus equivariant structure on the bundle.