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We obtain a locally symmetric Kaehler Einstein structure on the cotangent bundle of a Riemannian manifold of negative constant sectional curvature. Similar results are obtained on a tube around zero section in the cotangent bundle, in the…

Differential Geometry · Mathematics 2007-05-23 D. D. Porosniuc

Given a noncollapsing sequence of m-dimensional compact Einstein manifolds with a uniform energy bound, the Gromov-Hausdorff limit is a compact Einstein orbifold with at most finitely many singularities. Conversely, starting with a compact…

Differential Geometry · Mathematics 2026-03-17 Yichen Yao

Reflection in a line in Euclidean 3-space defines an almost paracomplex structure on the space of all oriented lines, isometric with respect to the canonical neutral Kaehler metric. Beyond Euclidean 3-space, the space of oriented geodesics…

Differential Geometry · Mathematics 2022-05-11 Nikos Georgiou , Brendan Guilfoyle

We give an overview of progress on homogeneous Einstein metrics on large classes of homogeneous manifolds, such as generalized flag manifolds and Stiefel manifolds. The main difference between these two classes of homogeneous spaces is that…

Differential Geometry · Mathematics 2016-05-20 Andreas Arvanitoyeorgos

We relate a recently introduced non-local geometric invariant of compact strictly pseudoconvex Cauchy-Riemann (CR) manifolds of dimension 3 to various eta-invariants in CR geometry: on the one hand a renormalized eta-invariant appearing…

Differential Geometry · Mathematics 2007-05-23 Olivier Biquard , Marc Herzlich , Michel Rumin

We point out a simple construction of an infinite class of Einstein near-horizon geometries in all odd dimensions greater than five. Cross-sections of the horizons are inhomogeneous Sasakian metrics (but not Einstein) on S^3xS^2 and more…

High Energy Physics - Theory · Physics 2012-10-19 Hari K. Kunduri , James Lucietti

In the context of generalised geometry we investigate reductions to $SU(m)\times SU(m)$ together with an integrability condition which in dimension 6 describes the geometry of type II supergravity compactifications.

Differential Geometry · Mathematics 2015-06-26 Claus Jeschek , Frederik Witt

An almost Einstein manifold satisfies equations which are a slight weakening of the Einstein equations; Einstein metrics, Poincare-Einstein metrics, and compactifications of certain Ricci-flat asymptotically locally Euclidean structures are…

Differential Geometry · Mathematics 2008-03-26 A. Rod Gover

In this article, we investigate the geometry of compact quasi-Einstein manifolds with boundary. We show that a $3$-dimensional simply connected compact quasi-Einstein manifold with boundary and constant scalar curvature is isometric, up to…

Differential Geometry · Mathematics 2026-04-10 Johnatan Costa , Ernani Ribeiro , Detang Zhou

In this article we show that in any dimension there exist infinitely many pairs of formally contact isotopic isocontact embeddings into the standard contact sphere which are not contact isotopic. This is the first example of rigidity for…

Symplectic Geometry · Mathematics 2019-12-11 Roger Casals , John B. Etnyre

Using Lie groups with left-invariant complex structure, we construct new examples of compact complex manifolds with flat affine structure in arbitrarly high dimensions. In the 2-dimensional case, we retrieve the Inoue surfaces $S^+$.

Differential Geometry · Mathematics 2024-10-03 David Petcu

The main result states that a connected conic singular sub-manifold of a Riemannian manifold, compact when the ambient manifold is non-Euclidean, is Lipschitz Normally Embedded: the outer and inner metric space structures are metrically…

Differential Geometry · Mathematics 2023-06-27 André Costa , Vincent Grandjean , Maria Michalska

We generalise the notion of contact manifold by allowing the contact distribution to have codimension two. There are special features in dimension six. In particular, we show that the complex structure on a three-dimensional complex contact…

Differential Geometry · Mathematics 2007-05-23 Andreas Cap , Michael Eastwood

Recently there has been an increasing interest in the study of generalized symmetries in dimensions higher than two. This has lead to the discovery of various manifestations of generalized symmetries, notably higher-group and non-invertible…

High Energy Physics - Theory · Physics 2024-03-26 Emily Nardoni , Matteo Sacchi , Orr Sela , Gabi Zafrir , Yunqin Zheng

The twistor construction for Riemannian manifolds is extended to the case of manifolds endowed with generalized metrics (in the sense of generalized geometry \`a la Hitchin). The generalized twistor space associated to such a manifold is…

Differential Geometry · Mathematics 2018-07-03 Johann Davidov

In this paper we construct and study almost paracontact metric structures $(\varphi ,\xi ,\eta ,g)$ on a 3-dimensional Walker manifold $(M,g)$ with respect to a local basis only by the coordinate functions of a unit space-like vector field…

Differential Geometry · Mathematics 2025-09-29 Galia Nakova , Cornelia-Livia Bejan

We construct a natural generalized complex structure on the total space of any bundle endowed with a Chern connection and whose typical fibre is a homogeneous symplectic manifold. This extends known constructions of generalized complex…

Differential Geometry · Mathematics 2013-04-09 Radu Pantilie

We obtain a class of locally symmetric Kaehler Einstein structures on the cotangent bundle of a Riemannian manifold of negative sectional curvature. Similar results are obtained in the case of a Riemannian manifold of positive sectional…

Differential Geometry · Mathematics 2007-05-23 D. D. Porosniuc

In this paper, we discuss two well-known open problems in the regularity theory for nonlinear, conformally invariant elliptic systems in dimensions $n\ge 3$, with a critical nonlinearity: $H$-systems (equations of hypersurfaces of…

Analysis of PDEs · Mathematics 2016-06-28 Armin Schikorra , Paweł Strzelecki

In this paper we compute the first and second variation of the normalized Einstein-Hilbert functional on CR manifolds. We characterize critical points as pseudo-Einstein structures. We then turn to the second variation on standard spheres.…

Differential Geometry · Mathematics 2023-06-14 Claudio Afeltra , Jih-Hsin Cheng , Andrea Malchiodi , Paul Yang