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We study compact complex $3$-dimensional non-K\"ahler Bismut Ricci flat pluriclosed Hermitian manifolds (BHE) via their dimensional reduction to a special K\"ahler geometry in complex dimension $2$, recently obtained by Barbaro, Streets and…

Differential Geometry · Mathematics 2026-01-30 Vestislav Apostolov , Abdellah Lahdili , Kuan-Hui Lee

Let {(M,g_i)} be a sequence of smooth compact oriented Einstein 4-manifolds of fixed Einstein constant $\lambda > 0$ that Gromov-Hausdorff converges to a 4-dimensional Einstein orbifold X. Suppose, moreover, that the limit metric is…

Differential Geometry · Mathematics 2026-02-09 Claude LeBrun , Tristan Ozuch

Let X be a compact Riemann surface equipped with a real-analytic K\"ahler form $\omega$ and let E be a holomorphic vector bundle over $X$ equipped with a real-analytic Hermitian metric $h$. Suppose that the curvature of $h$ is…

Complex Variables · Mathematics 2025-06-02 Shin Kim

The fundamental group of a Riemannian manifold with $\delta$-pinched negative curvature, $\delta >1/4$, cannot be the fundamental group of a quasicompact K\"ahler manifold. The proof also implies that a non-uniform lattice in $F_{4(-20)}$…

Differential Geometry · Mathematics 2007-05-23 Juergen Jost , Yihu Yang

A Hermitian-symplectic metric is a Hermitian metric whose K\"ahler form is given by the $(1,1)$-part of a closed $2$-form. Streets-Tian Conjecture states that a compact complex manifold admitting a Hermitian-symplectic metric must be…

Differential Geometry · Mathematics 2025-03-18 Shuwen Chen , Fangyang Zheng

We argue that the Einstein gravity theory can be reformulated in almost Kahler (nonsymmetric) variables with effective symplectic form and compatible linear connection uniquely defined by a (pseudo) Riemannian metric. A class of…

General Relativity and Quantum Cosmology · Physics 2009-07-24 Sergiu I. Vacaru

We study non-Einstein Bach-flat gravitational instanton solutions that can be regarded as the generalization of the Taub-NUT/Bolt and Eguchi-Hanson solutions of Einstein gravity to conformal gravity. These solutions include non-Einstein…

High Energy Physics - Theory · Physics 2021-09-15 Cristóbal Corral , Gastón Giribet , Rodrigo Olea

Let $X$ denote a noncompact finite volume hyperbolic Riemann surface of genus $g\geq 2$, with only one puncture at $i\infty$ (identifying $X$ with its universal cover $\mathbb{H}$). Let $\overline{X}:=X\cup\lbrace i\infty\rbrace$ denote the…

Complex Variables · Mathematics 2024-05-24 Anilatmaja Aryasomayajula , Arijit Mukherjee

We construct an example of an asymptotically conical (AC) non-K\"ahler expanding gradient Ricci soliton that has a K\"ahler tangent cone at infinity. This yields an example of a K\"ahler cone that can be desingularised by a smooth AC…

Differential Geometry · Mathematics 2026-03-27 Richard H. Bamler , Eric Chen , Ronan J. Conlon

We present explicit constructions of complete Ricci-flat Kahler metrics that are asymptotic to cones over non-regular Sasaki-Einstein manifolds. The metrics are constructed from a complete Kahler-Einstein manifold (V,g_V) of positive Ricci…

Differential Geometry · Mathematics 2009-07-22 Dario Martelli , James Sparks

For an asymptotically locally Euclidean (ALE) or asymptotically locally flat (ALF) gravitational instanton $(M,g)$ with toric symmetry, we express the signature of $(M,g)$ directly in terms of its rod structure. Applying…

Differential Geometry · Mathematics 2024-08-02 Gustav Nilsson

In this paper, we study the topology of complete noncompact Riemannian manifolds with asymptotically nonnegative Ricci curvature and large volume growth. We prove that they have finite topological types under some curvature decay and volume…

Differential Geometry · Mathematics 2014-08-19 Yuntao Zhang

In this work we investigate Ricci flows of almost Kaehler structures on Lie algebroids when the fundamental geometric objects are completely determined by (semi) Riemannian metrics, or effective) regular generating Lagrange/ Finsler,…

Differential Geometry · Mathematics 2016-03-25 Sergiu I. Vacaru

Let (M,h) be a compact 4-dimensional Einstein manifold, and suppose that h is Hermitian with respect to some complex structure J on M. Then either (M,J,h) is Kaehler-Einstein, or else, up to rescaling and isometry, it is one of the…

Differential Geometry · Mathematics 2010-10-04 Claude LeBrun

In this paper we give new examples of QCH Kahler surfaces whose opposite almost Hermitian strucure is Hermitian and not locally conformally Kahler. In this way we give also a large class of examples of Hermitian surfaces with J-invariant…

Differential Geometry · Mathematics 2020-05-18 Wlodzimierz Jelonek

Any oriented $4$-dimensional Einstein metric with semi-definite sectional curvature satisfies the pointwise inequality \[ \frac{|s|}{\sqrt{6}}\geq|W^+|+|W^-|, \] where $s$, $W^+$ and $W^-$ are respectively the scalar curvature, the…

Differential Geometry · Mathematics 2025-03-28 Luca F. Di Cerbo

This paper is concerned with the construction of special metrics on non-compact 4-manifolds which arise as resolutions of complex orbifold singularities. Our study is close in spirit to the construction of the hyperkaehler gravitational…

Differential Geometry · Mathematics 2015-06-26 David M. J. Calderbank , Michael A. Singer

We describe and construct here pseudo-Hermitian structures $\theta$ without torsion (i.e. with transversal symmetry) whose Webster-Ricci curvature tensor is a constant multiple of the exterior differential $d\theta$. We call these…

Differential Geometry · Mathematics 2007-05-23 Felipe Leitner

We survey the authors recent works, joint with A. Jacob, on Strominger-Yau-Zaslow mirror symmetry for rational elliptic surfaces and del Pezzo surfaces. We discuss some applications, including the Torelli theorem for $ALH^*$ gravitational…

Differential Geometry · Mathematics 2022-09-01 Tristan C. Collins , Yu-Shen Lin

In this paper, we investigate the geometry of asymptotically flat manifolds with controlled holonomy. We show that any end of such manifold admits a torus fibration over an ALE end. In addition, we prove a Hitchin-Thorpe inequality for…

Differential Geometry · Mathematics 2021-09-15 Xiuxiong Chen , Yu Li