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We construct infinitely many seven-dimensional Einstein metrics of weak holonomy G_2. These metrics are defined on principal SO(3) bundles over four-dimensional Bianchi IX orbifolds with the Tod-Hitchin metrics. The Tod-Hitchin metric has…

High Energy Physics - Theory · Physics 2015-06-26 Makoto Sakaguchi , Yukinori Yasui

The strong unique continuation property for Einstein metrics can be concluded from the well-known fact that Einstein metrics are analytic in geodesic normal coordinates. Here we give a proof of the same result that given two Einstein…

Analysis of PDEs · Mathematics 2014-01-27 Willie Wai-Yeung Wong , Pin Yu

In this paper we prove the existence of rational homology balls smoothly embedded in regular neighborhoods of certain linear chains of smooth $2$-spheres by using techniques from minimal model program for 3-dimensional complex algebraic…

Geometric Topology · Mathematics 2015-08-18 Heesang Park , Jongil Park , Dongsoo Shin

Minimal surfaces and Einstein manifolds are among the most natural structures in differential geometry. Whilst minimal surfaces are well understood, Einstein manifolds remain far less so. This exposition synthesises together a set of…

Differential Geometry · Mathematics 2025-08-19 Mia Beard

A new infinite series of Einstein metrics is constructed explicitly on S^2 x S^3, and the non-trivial S^3-bundle over S^2, containing infinite numbers of inhomogeneous ones. They appear as a certain limit of a nearly extreme 5-dimensional…

High Energy Physics - Theory · Physics 2009-11-10 Yoshitake Hashimoto , Makoto Sakaguchi , Yukinori Yasui

We study quiver gauge theories on the round and squashed seven-spheres, and orbifolds thereof. They arise by imposing $G$-equivariance on the homogeneous space $G/H=\mathrm{SU}(4)/\mathrm{SU}(3)$ endowed with its Sasaki-Einstein structure,…

High Energy Physics - Theory · Physics 2019-03-26 Jakob C. Geipel , Olaf Lechtenfeld , Alexander D. Popov , Richard J. Szabo

Most known four-dimensional cohomogeneity-one Einstein metrics are diagonal in the basis defined by the left-invariant one-forms, though some essentially non-diagonal ones are known. We consider the problem of explicitly seeking…

General Relativity and Quantum Cosmology · Physics 2016-09-15 Maciej Dunajski , Paul Tod

The Newman-Penrose-Perjes formalism is applied to Sasakian 3-manifolds and the local form of the metric and contact structure is presented. The local moduli space can be parameterised by a single function of two variables and it is shown…

Differential Geometry · Mathematics 2021-11-15 Brendan S. Guilfoyle

The authors examine topological properties of the 7-dimensional Eschenburg biquotients diag(z^k1,z^k2,z^k3)\SU(3)/diag(z^l1,z^l2,z^l3). A subfamily of these spaces carry a 3-Sasakian metric. The authors show that among this subfamily there…

Differential Geometry · Mathematics 2007-05-23 Ted Chinburg , Christine Escher , Wolfgang Ziller

We construct several examples of compactifications of Einstein metrics. We show that the Eguchi--Hanson instanton admits a projective compactification which is non--metric, and that a metric cone over any (pseudo)--Riemannian manifolds…

Differential Geometry · Mathematics 2020-02-12 Maciej Dunajski , A. Rod Gover , Alice Waterhouse

In this paper, we study an important class of Finsler metrics--square metrics. We give two expressions of such metrics in terms of a Riemannian metric and a 1-form. We show that Einstein square metrics can be classified up to the…

Differential Geometry · Mathematics 2012-09-19 Zhongmin Shen , Changtao Yu

On $4$-symmetric symplectic spaces, invariant almost complex structures -- up to sign -- arise in pairs. We exhibit some $4$-symmetric symplectic spaces, with a pair of "natural" compatible (usually not positive) invariant almost complex…

Differential Geometry · Mathematics 2022-06-14 Michel Cahen , Simone Gutt , Manar Hayyani , Mohammed Raouyane

We prove a Theorem on homotheties between two given tangent sphere bundles $S_rM$ of a Riemannian manifold $M,g$ of $\dim\geq 3$, assuming different variable radius functions $r$ and weighted Sasaki metrics induced by the conformal class of…

Differential Geometry · Mathematics 2019-07-25 Rui Albuquerque

We find the precise number of non-K\"ahler $Sp(n)$-invariant Einstein metrics on the generalized flag manifold $M=Sp(n)/(U(p)\times U(n-p))$ with $n\geq 3$ and $1\leq p\leq n-1$. We use an analysis on parametric systems of polynomial…

Differential Geometry · Mathematics 2017-01-10 Andreas Arvanitoyeorgos , Ioannis Chrysikos , Yusuke Sakane

We show that all compact quasi-Einstein metrics of constant scalar curvature in dimension three are locally homogeneous. We accomplish this by using the equivalence of constant scalar curvature quasi-Einstein metrics $(M,g,X)$ and…

Differential Geometry · Mathematics 2025-12-24 Eric Cochran

A Riemann-Cartan manifold is a Riemannian manifold endowed with an affine connection which is compatible with the metric tensor. This affine connection is not necessarily torsion free. Under the assumption that the manifold is a homogeneous…

Differential Geometry · Mathematics 2019-09-04 Cristina Draper , Antonio Garvín , Francisco J. Palomo

This is a survey on the correspondence between asymptotically complex hyperbolic Einstein metrics and CR structures on the boundary at infinity, which is the complex version of that between Poincar\'e-Einstein metrics and conformal…

Differential Geometry · Mathematics 2018-03-29 Yoshihiko Matsumoto

We define and study natural $\mathrm{SU}(2)$-structures, in the sense of Conti-Salamon, on the total space $\cal S$ of the tangent sphere bundle of any given oriented Riemannian 3-manifold $M$. We recur to a fundamental exterior…

Differential Geometry · Mathematics 2020-10-19 R. Albuquerque

We construct continuous families of Riemannian metrics on certain simply connected manifolds with the property that the resulting Riemannian manifolds are pairwise isospectral for the Laplace operator acting on functions. These are the…

dg-ga · Mathematics 2007-05-23 Dorothee Schueth

We consider homogeneous spaces of Lie groups with compact stabilizer subgroups of two types: those with integrable invariant distributions and those with geodesic orbit invariant Riemannian metrics. The latter means that for an arbitrary…

Differential Geometry · Mathematics 2026-01-13 V. N. Berestovskii , Yu. G. Nikonorov