Invariant almost contact structure on the real extension of a sphere

The existence of contact and almost contact metric structures invariant under the group of motions on the real extension of a two-dimensional sphere with a Riemannian direct product metric was examined. The basis vector fields of the Lie algebra associated with the Lie group of motions were found. T...

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Main Authors: M. V. Sorokina, Y. V. Morshchinkina
Format: Article
Language:English
Published: Kazan Federal University 2025-04-01
Series:Учёные записки Казанского университета: Серия Физико-математические науки
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Online Access:https://uzakufismat.elpub.ru/jour/article/view/159
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author M. V. Sorokina
Y. V. Morshchinkina
author_facet M. V. Sorokina
Y. V. Morshchinkina
author_sort M. V. Sorokina
collection DOAJ
description The existence of contact and almost contact metric structures invariant under the group of motions on the real extension of a two-dimensional sphere with a Riemannian direct product metric was examined. The basis vector fields of the Lie algebra associated with the Lie group of motions were found. The results obtained show that invariant contact structures do not exist, but there is an almost contact metric structure, which is integrable, normal, and has a closed fundamental form, thus making it quasi-Sasakian. The Lie group of automorphisms of this structure coincides with the group of motions and has the maximum possible dimension. All linear connections were found that are invariant under the automorphism group and in which the structural tensors of the quasi-Sasakian structure are covariantly constant. Each such connection is uniquely determined by the quasi-Sasakian structure and by fixing one constant. It was established that the contact distribution of the almost contact structure is completely geodesic. Therefore, the derived connections are consistent with this distribution.
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id doaj-art-b099a1ed7acd4607abc3282040229bb3
institution Kabale University
issn 2541-7746
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language English
publishDate 2025-04-01
publisher Kazan Federal University
record_format Article
series Учёные записки Казанского университета: Серия Физико-математические науки
spelling doaj-art-b099a1ed7acd4607abc3282040229bb32025-08-20T03:51:48ZengKazan Federal UniversityУчёные записки Казанского университета: Серия Физико-математические науки2541-77462500-21982025-04-01167114014910.26907/2541-7746.2025.1.140-14983Invariant almost contact structure on the real extension of a sphereM. V. Sorokina0Y. V. Morshchinkina1Penza State UniversityPenza State UniversityThe existence of contact and almost contact metric structures invariant under the group of motions on the real extension of a two-dimensional sphere with a Riemannian direct product metric was examined. The basis vector fields of the Lie algebra associated with the Lie group of motions were found. The results obtained show that invariant contact structures do not exist, but there is an almost contact metric structure, which is integrable, normal, and has a closed fundamental form, thus making it quasi-Sasakian. The Lie group of automorphisms of this structure coincides with the group of motions and has the maximum possible dimension. All linear connections were found that are invariant under the automorphism group and in which the structural tensors of the quasi-Sasakian structure are covariantly constant. Each such connection is uniquely determined by the quasi-Sasakian structure and by fixing one constant. It was established that the contact distribution of the almost contact structure is completely geodesic. Therefore, the derived connections are consistent with this distribution.https://uzakufismat.elpub.ru/jour/article/view/159real extension of spherealmost contact structureinfinitesimal automorphismalmost contact metric connection
spellingShingle M. V. Sorokina
Y. V. Morshchinkina
Invariant almost contact structure on the real extension of a sphere
Учёные записки Казанского университета: Серия Физико-математические науки
real extension of sphere
almost contact structure
infinitesimal automorphism
almost contact metric connection
title Invariant almost contact structure on the real extension of a sphere
title_full Invariant almost contact structure on the real extension of a sphere
title_fullStr Invariant almost contact structure on the real extension of a sphere
title_full_unstemmed Invariant almost contact structure on the real extension of a sphere
title_short Invariant almost contact structure on the real extension of a sphere
title_sort invariant almost contact structure on the real extension of a sphere
topic real extension of sphere
almost contact structure
infinitesimal automorphism
almost contact metric connection
url https://uzakufismat.elpub.ru/jour/article/view/159
work_keys_str_mv AT mvsorokina invariantalmostcontactstructureontherealextensionofasphere
AT yvmorshchinkina invariantalmostcontactstructureontherealextensionofasphere