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We show that for all $n \geq 2$, there exists a doubling linearly locally contractible metric space $X$ that is topologically a $n$-sphere such that every weak tangent is isometric to $\R^n$ but $X$ is not quasisymmetrically equivalent to…

Metric Geometry · Mathematics 2018-06-11 Angela Wu

We study the class of vacuum (Ricci flat) six-dimensional spacetimes admitting a non-degenerate multiple Weyl aligned null direction l, thus being of Weyl type II or more special. Subject to an additional assumption on the asymptotic…

General Relativity and Quantum Cosmology · Physics 2017-06-26 Marcello Ortaggio

Within a semiclassical framework, we investigate spherically symmetric solutions of the Einstein equations that (i) develop a trapped region within a finite time as measured by distant observers, and (ii) remain sufficiently regular at the…

General Relativity and Quantum Cosmology · Physics 2025-09-16 Swayamsiddha Maharana , Rama Vadapalli

We find a plethora of new analytic black holes and globally regular horizonless spacetimes in three dimensions. The solutions involve a single real scalar field $\phi$ which always admits a magnetic-like expression proportional to the…

General Relativity and Quantum Cosmology · Physics 2021-07-07 Pablo Bueno , Pablo A. Cano , Javier Moreno , Guido van der Velde

We show that the exact solution of Einstein's equations describing a system of two aligned identical Kerr black holes separated by a massless strut follows straightforwardly from the extended 2-soliton solution possessing equatorial…

General Relativity and Quantum Cosmology · Physics 2017-11-22 V. S. Manko , E. Ruiz

Using the tractor calculus to study smooth metric measure spaces, we adapt results of Gover and Nurowski to give sharp metric obstructions to the existence of quasi-Einstein metrics on suitably generic manifolds. We do this by introducing…

Differential Geometry · Mathematics 2012-05-04 Jeffrey S. Case

We obtain infinite classes of new Einstein-Sasaki metrics on complete and non-singular manifolds. They arise, after Euclideanisation, from BPS limits of the rotating Kerr-de Sitter black hole metrics. The new Einstein-Sasaki spaces…

High Energy Physics - Theory · Physics 2009-09-17 M. Cvetic , H. Lu , Don N. Page , C. N. Pope

We extend the following result of Cochran ``A closed $m$-quasi Einstein manifold ($M,g,X$) with $m \ne -2$ has constant scalar curvature if and only if $X$ is Killing" covering the missing accidental case $m=-2$ and generalize it showing…

Differential Geometry · Mathematics 2025-05-15 Ramesh Sharma

We provide an explicit resolution of the existence problem for extremal Kaehler metrics on toric 4-orbifolds M with second Betti number b2(M)=2. More precisely we show that M admits such a metric if and only if its rational Delzant polytope…

Differential Geometry · Mathematics 2016-11-28 Vestislav Apostolov , David M. J. Calderbank , Paul Gauduchon

We extend Tsuji's iterative construction of complete K\"ahler--Einstein metrics with negative scalar curvature to noncompact K\"ahler manifolds with bounded geometry, using Berndtsson's method from the compact setting. Consequently, given a…

Differential Geometry · Mathematics 2026-01-13 Quang-Tuan Dang , Tat Dat Tô

A Riemannian metric is of constant curvature if and only if it is locally projectively flat. There are infinitely many locally projectively flat Finsler metrics of constant curvature, that are special solutions to the Hilbert's Fourth…

Differential Geometry · Mathematics 2007-05-23 Zhongmin Shen

We discuss smooth metric measure spaces admitting two weighted Einstein representatives of the same weighted conformal class. First, we describe the local geometries of such manifolds in terms of certain Einstein and quasi-Einstein warped…

Differential Geometry · Mathematics 2025-04-11 Miguel Brozos-Vázquez , Eduardo García-Río , Diego Mojón-Álvarez

A smooth closed manifold $M$ is called almost Ricci-flat if $$\inf_g||\textrm{Ric}_g||_\infty\cdot \textrm{diam}_g(M)^2=0$$ where $\textrm{Ric}_g$ and $\textrm{diam}_g$ denote the Ricci tensor and the diameter of $g$ respectively and $g$…

Differential Geometry · Mathematics 2023-04-03 Chanyoung Sung

This paper investigates the interplay between the geometric and topological properties of spherically symmetric black hole metrics within Einstein gravity, emphasizing implications for Bose-Einstein Condensation (BEC). By analyzing metric…

General Physics · Physics 2024-10-10 Wen-Xiang Chen

We construct new complete Einstein metrics on smoothly bounded strictly pseudoconvex domains in Stein manifolds. This is done by deforming the K\"ahler-Einstein metric of Cheng and Yau, the approach that generalizes the works of Roth and…

Differential Geometry · Mathematics 2019-07-01 Yoshihiko Matsumoto

We investigate the quasisymmetric uniformization of a special class of metric surfaces known as paper surfaces, constructed as quotients of planar multipolygons via segment pairings, including infinite Type W identifications. These spaces,…

Metric Geometry · Mathematics 2026-02-12 Luciana Menezes Vasconcelos

A static spherically symmetric metric in Einstein-scalar-tensor gravity theory with a scalar field potential $V[\phi]$ is non-singular for all real values of the coordinates. It does not have a black hole event horizon and there is no…

General Relativity and Quantum Cosmology · Physics 2008-06-11 J. W. Moffat

In this paper, we investigate the numerical solutions for spherically symmetric situations in Einstein cubic gravity. In addition to the previously found black hole solutions, we uncover a new class of solutions that lack horizons. Due to…

General Relativity and Quantum Cosmology · Physics 2024-10-08 Yong-Qiang Wang

We find necessary and sufficient conditions for a Riemannian four-dimensional manifold $(M, g)$ with anti-self-dual Weyl tensor to be locally conformal to a Ricci--flat manifold. These conditions are expressed as the vanishing of scalar and…

High Energy Physics - Theory · Physics 2015-06-15 Maciej Dunajski , Paul Tod

We provide a geometric framework for the construction of non-vacuum black holes whose metrics are stationary and axisymmetric. Under suitable assumptions we show that the Einstein equations reduce to an Einstein-harmonic map type system and…

General Relativity and Quantum Cosmology · Physics 2015-10-28 Otis Chodosh , Yakov Shlapentokh-Rothman