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The k-systole of a Riemannian manifold is the infimum of the volume over all homologically non-trivial k-cycles. In this paper we discuss the behavior of the dimension two and co-dimension two systole of the complex projective space for…

Differential Geometry · Mathematics 2026-02-02 Luciano L. Junior

We obtain a simple explicit expression for the hyper-Kahler Calabi metric on the co-tangent bundle of CP^{n+1}, for all n, in which it is constructed as a metric of cohomogeneity one with SU(n+2)/U(n) principal orbits. These results enable…

High Energy Physics - Theory · Physics 2009-09-17 M. Cvetic , G. W. Gibbons , H. Lu , C. N. Pope

We prove rigidity and gap theorems for self-dual and even Poincar\'e-Einstein metrics in dimension four. As a corollary, we give an obstruction to the existence of self-dual Poincar\'e-Einstein metrics in terms of conformal invariants of…

Differential Geometry · Mathematics 2024-07-15 Matthew J. Gursky , Stephen E. McKeown , Aaron J. Tyrrell

Let X be a compact 4-manifold with boundary. We study the space of hyperk\"ahler triples on X, modulo diffeomorphisms which are the identity on the boundary. We prove that this moduli space is a smooth infinite-dimensional manifold and…

Differential Geometry · Mathematics 2017-05-16 Joel Fine , Jason D. Lotay , Michael Singer

We construct new explicit non-singular metrics that are complete on non-compact Riemannian 8-manifolds with holonomy Spin(7). One such metric, which we denote by A_8, is complete and non-singular on R^8. The other complete metrics are…

Differential Geometry · Mathematics 2009-09-17 M. Cvetic , G. W. Gibbons , H. Lu , C. N. Pope

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 show that given a conformal structure whose holonomy representation fixes a totally lightlike subspace of arbitrary dimension, there is always a local metric in the conformal class off a singular set which is Ricci-isotropic and gives…

Differential Geometry · Mathematics 2014-08-12 Andree Lischewski

The paper is part of an attempt of understanding non-K\"ahler threefolds. We start by looking at compact complex non-K\"ahler threefolds with algebraic dimension two and admitting locally conformally K\"ahler metrics. Under certain…

Differential Geometry · Mathematics 2023-03-21 Daniele Angella , Maurizio Parton , Victor Vuletescu

In the paper we consider pseudo bihermitian structures - a pair of complex structures compatible with a pseudo Riemannian metric. As in the positive definite case we establish its relations with generalized (pseudo) Kaehler geometry and…

Differential Geometry · Mathematics 2011-04-22 J. Davidov , G. Grantcharov , O. Muskarov , M. Yotov

The coadjoint orbits of compact Lie groups each carry a canonical (positive definite) K\"ahler structure, famously used to realize the group's irreducible representations in holomorphic sections of appropriate line bundles (Borel-Weil…

Differential Geometry · Mathematics 2022-11-30 Thomas Mason , Francois Ziegler

The property of admitting an astheno-K\"ahler metric is not stable under the action of small deformations of the complex structure of a compact complex manifold. In this paper, we prove necessary cohomological conditions for the existence…

Differential Geometry · Mathematics 2023-05-08 Tommaso Sferruzza

In this article we study the stability problem for positive quaternion-K\"ahler manifolds. We give a description of infinitesimal Einstein deformations and destabilising directions in terms of Laplace eigenfunctions and a special class of…

Differential Geometry · Mathematics 2026-04-03 Yasushi Homma , Uwe Semmelmann

Let $\mathcal{K}(n, V)$ be the set of $n$-dimensional compact Kahler-Einstein manifolds $(X, g)$ satisfying $Ric(g)= - g$ with volume bounded above by $V$. We prove that after passing to a subsequence, any sequence $\{ (X_j,…

Differential Geometry · Mathematics 2020-03-11 Jian Song , Jacob Sturm , Xiaowei Wang

Let X be a K\"ahler manifold and D be a R-divisor with simple normal crossing support and coefficients between 1/2 and 1. Assuming that K_X+D is ample, we prove the existence and uniqueness of a negatively curved Kahler-Einstein metric on…

Complex Variables · Mathematics 2012-01-05 Henri Guenancia

Given an oriented Riemannian surface $(\Sigma, g)$, its tangent bundle $T\Sigma$ enjoys a natural pseudo-K\"{a}hler structure, that is the combination of a complex structure $\J$, a pseudo-metric $\G$ with neutral signature and a symplectic…

Differential Geometry · Mathematics 2017-02-08 Henri Anciaux , Brendan Guilfoyle , Pascal Romon

The main focus of the paper is the investigation of moduli space of left invariant pseudoRiemannian metrics on the cotangent bundle of Heisenberg group. Consideration of orbits of the automorphism group naturally acting on the space of the…

Differential Geometry · Mathematics 2021-09-02 Tijana Sukilovic , Srdjan Vukmirovic , Neda Bokan

We study the group properties and the similarity solutions for the constraint conditions of anti-self-dual null K\"{a}hler four-dimensional manifolds with at least a Killing symmetry vector. Specifically we apply the theory of Lie…

General Relativity and Quantum Cosmology · Physics 2021-06-08 Andronikos Paliathanasis

We construct Bridgeland stability conditions on the the following hyper-K\"ahler or strict Calabi--Yau manifolds: - Generalized Kummer varieties associated to an abelian surface that is isogenous to a product of elliptic curves. - Universal…

Algebraic Geometry · Mathematics 2025-10-28 Yiran Cheng

We classify the supersymmetric solutions of minimal $N=2$ gauged supergravity in four dimensions with neutral signature. They are distinguished according to the sign of the cosmological constant and whether the vector field constructed as a…

High Energy Physics - Theory · Physics 2015-09-23 Dietmar Klemm , Masato Nozawa

We find new conditions that the existence of nullity of the curvature tensor of an irreducible homogeneous space $M=G/H$ imposes on the Lie algebra $\mathfrak g$ of $G$ and on the Lie algebra $\tilde{\mathfrak g}$ of the full isometry group…

Differential Geometry · Mathematics 2022-07-06 Antonio J. Di Scala , Carlos E. Olmos , Francisco Vittone