Conformal Einstein spaces and Bach tensor generalizations in n dimensions
2004 (English)Licentiate thesis, monograph (Other academic)
Abstract [en]
In this thesis we investigate necessary and sufficient conditions for an n-dimensional space, n ≥ 4, to be locally conformal to an Einstein space. After reviewing the classical results derived in tensors we consider the four-dimensional spinor result of Kozameh, Newman and Tod. The involvement of the four-dimensional Bach tensor (which is divergence-free and conformally well-behaved) in their result motivates a search for an n-dimensional generalization of the Bach tensor Bab with the same properties. We strengthen a theorem due to Belfagón and Jaen and give a basis (Uab, Vab and Wab) for all n-dimensional symmetric, divergence-free 2-index tensors quadratic in the Riemann curvature tensor. We discover the simple relationship
and show that the Bach tensor is the unique tensor with these properties in four dimensions. Unfortunately we have to conclude, in general that there is no direct analogue in higher dimension with all these properties.
Nevertheless, we are able to generalize the four-dimensional results due to Kozameh, Newman and Tod to n dimensions. We show that a generic space is conformal to an Einstein space if and only if there exists a vector field satisfying two conditions. The explicit use of dimensionally dependent identities (some of which are newly derived in this thesis) is also exploited in order to make the two conditions as simple as possible; explicit examples are given in five and six dimensions using these tensor identities.
For n dimensions, we define the tensors 𝔟abc and 𝔅ab, and we show that their vanishing is a conformal invariant property which guarantees that the space with non-degenerate Weyl tensor is a conformal Einstein space.
Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 2004. , p. 90
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1113
National Category
Mathematics
Identifiers
URN: urn:nbn:se:liu:diva-152989Local ID: LiU-TEK-LIC-2004:42ISBN: 9185295280 (print)OAI: oai:DiVA.org:liu-152989DiVA, id: diva2:1288862
Presentation
2004-09-24, Glashuset, Hus B, ing. 25, Campus Valla, 10:15 (Swedish)
Opponent
2019-02-142019-02-142022-01-25Bibliographically approved