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This article presents a new and more elementary proof of the main Seiberg-Witten-based obstruction to the existence of Einstein metrics on smooth compact 4-manifolds. It also introduces a new smooth manifold invariant which conveniently…

Differential Geometry · Mathematics 2007-05-23 Claude LeBrun

Linear connections satisfying the Einstein metricity condition are important in the study of generalized Riemannian manifolds $(M,G=g+F)$, where the symmetric part $g$ of $G$ is a non-degenerate $(0,2)$-tensor, and $F$ is the skew-symmetric…

Differential Geometry · Mathematics 2025-08-12 Milan Zlatanović , Vladimir Rovenski

Page's Einstein metric on CP_2 # (-CP_2) is conformally related to an extremal Kaehler metric. Here we construct a family of conformally K\"ahler solutions of the Einstein-Maxwell equations that deforms the Page metric, while sweeping out…

Differential Geometry · Mathematics 2016-03-23 Claude LeBrun

The aim of this note is the study of Einstein condition for para-holomorphic Riemannian metrics in the para-complex geometry framework. Firstly, we make some general considerations about para-complex Riemannian manifolds (not necessarily…

Differential Geometry · Mathematics 2016-10-12 Cristian Ida , Alexandru Ionescu , Adelina Manea

In this paper, using special metric deformations introduced by Aubin, we construct Riemannian metrics satisfying non-vanishing conditions concerning the Weyl tensor, on every compact manifold. In particular, in dimension four, we show that…

Differential Geometry · Mathematics 2024-09-12 Giovanni Catino , Davide Dameno , Paolo Mastrolia

In the present work some examples of toric hyperkahler metrics in eight dimensions are constructed. First it is described how the Calderbank-Pedersen metrics arise as a consequence of the Joyce description of selfdual structures in four…

High Energy Physics - Theory · Physics 2009-11-10 O. P. Santillan , A. G. Zorin

Consider an Einstein orbifold $(M_0,g_0)$ of real dimension $2n$ having a singularity with orbifold group the cyclic group of order $n$ in ${\rm{SU}}(n)$ which is generated by an $n$th root of unity times the identity. Existence of a…

Differential Geometry · Mathematics 2019-02-25 Peyman Morteza , Jeff A. Viaclovsky

In this paper we construct Einstein spaces with negative Ricci curvature in various dimensions. These spaces -- which can be thought of as generalised AdS spacetimes -- can be classified in terms of the geometry of the horospheres in…

High Energy Physics - Theory · Physics 2008-11-26 Sigbjorn Hervik

We investigate the Einstein equation with a positive cosmological constant for $4n+4$-dimensional metrics on bundles over Quaternionic K\"ahler base manifolds whose fibers are 4-dimensional Bianchi IX manifolds. The Einstein equations are…

High Energy Physics - Theory · Physics 2009-11-10 Mitsuo Hiragane , Yukinori Yasui , Hideki Ishihara

This paper considers the existence of conformally compact Einstein metrics on 4-manifolds. A reasonably complete understanding is obtained for the existence of such metrics with prescribed conformal infinity, when the conformal infinity is…

Differential Geometry · Mathematics 2008-03-18 Michael T. Anderson

We construct, using harmonic superspace and the quaternionic quotient approach, a quaternionic-K\"ahler extension of the most general two centres hyper-K\"ahler metric. It possesses $U(1)\times U(1)$ isometry, contains as special cases the…

High Energy Physics - Theory · Physics 2009-11-07 Pierre-Yves Casteill , Evgeny Ivanov , Galliano Valent

We study invariant pseudo-K\"ahler structures on a solvmanifold $G$ such that the Lie algebra $\mathfrak{g}$ is almost abelian, that is $\mathfrak{g}=\mathfrak{h}\rtimes\mathbb{R}$, with $\mathfrak{h}$ abelian; comparing with the…

Differential Geometry · Mathematics 2025-06-30 Diego Conti , Alejandro Gil-García

Conditions for the existence of K\"ahler-Einstein metrics and central K\"ahler metrics [MS] along with examples, both old and new, are given on classes of Lorentzian $4$-manifolds with two distinguished vector fields. The results utilize…

Differential Geometry · Mathematics 2020-12-24 Amir Babak Aazami , Gideon Maschler

We present three families of exact, cohomogeneity-one Einstein metrics in $(2n+2)$ dimensions, which are generalizations of the Stenzel construction of Ricci-flat metrics to those with a positive cosmological constant. The first family of…

High Energy Physics - Theory · Physics 2019-04-26 M. Cvetic , G. W. Gibbons , C. N. Pope

We study the existence of projectable $G$-invariant Einstein metrics on the total space of $G$-equivariant fibrations $M=G/L\to G/K$, for a compact connected semisimple Lie group $G$. We obtain necessary conditions for the existence of such…

Differential Geometry · Mathematics 2009-11-15 Fatima Araujo

We examine Hermitian metrics on unimodular Lie algebras which contains a $J$-invariant abelian ideal of codimension two, and give a classification for all Bismut K\"ahler-like and all Bismut torsion-parallel metrics on such Lie algebras.

Differential Geometry · Mathematics 2024-07-23 Yuqin Guo , Fangyang Zheng

We prove certain weak or idealized existence results for minimizers of the natural quadratic curvature functionals on the space of metrics on 4-manifolds. Overall, we try to exhibit the relations with the picture in 3-dimensions provided by…

Differential Geometry · Mathematics 2007-05-23 Michael T. Anderson

The aim of this paper is to study Seifert bundle structures on simply connected 5--manifolds. We classify all such 5--manifolds which admit a Seifert bundle structure, and in a few cases all Seifert bundle structures are also classified.…

Differential Geometry · Mathematics 2007-05-23 János Kollár

In a previous paper, the first two authors classified complete Ricci-flat ALF Riemannian 4-manifolds that are toric and Hermitian, but non-Kaehler. In this article, we consider general Ricci-flat deformations of such spaces, assuming only…

Differential Geometry · Mathematics 2023-11-14 Olivier Biquard , Paul Gauduchon , Claude LeBrun

Fine and Premoselli (FP) constructed the first examples of manifolds that do not admit a locally symmetric metric but do admit a negatively curved Einstein metric. The manifolds here are hyperbolic branched covers like those used by Gromov…

Differential Geometry · Mathematics 2025-05-02 Jean-François Lafont , Barry Minemyer