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Let (M,J) be a compact complex 2-manifold which which admits a Kaehler metric for which the integral of the scalar curvature is non-negative. Also suppose that M does not admit a Ricci-flat K\"ahler metric. Then if M is blown up at…

dg-ga · Mathematics 2008-02-03 Jongsu Kim , Claude LeBrun , Massimiliano Pontecorvo

The theory of harmonic vector fields on Riemannian manifolds is generalised to pseudo-Riemannian manifolds. Harmonic conformal gradient fields on pseudo-Euclidean hyperquadrics are classified up to congruence, as are harmonic Killing fields…

Differential Geometry · Mathematics 2016-10-31 R. M. Friswell , C. M. Wood

We construct a moduli space of polarised manifolds which admit a constant scalar curvature K\"ahler metric. We show that this space admits a natural K\"ahler metric.

Algebraic Geometry · Mathematics 2025-04-01 Ruadhaí Dervan , Philipp Naumann

We determine the space of algebraic pseudo-Hermitian K\"ahler-Weyl curvature tensors and the space of para-Hermitian K\"ahler-Weyl curvature tensors in dimension 4 and show that every algebraic possibility is geometrically realizable. We…

Differential Geometry · Mathematics 2011-09-22 P. Gilkey , S. Nikcevic

We show that a closed almost K\"ahler 4-manifold of globally constant holomorphic sectional curvature $k\geq 0$ with respect to the canonical Hermitian connection is automatically K\"ahler. The same result holds for $k<0$ if we require in…

Differential Geometry · Mathematics 2017-09-18 Mehdi Lejmi , Markus Upmeier

We give a complete list of two-dimensional metrics that admit an essential projective vector field. This solves a problem explicitly posed by Sophus Lie in 1882.

Differential Geometry · Mathematics 2009-10-21 Vladimir S. Matveev

A study is made of 4-dimensional Lorentz manifolds which are projectively related, that is, whose Levi-Civita connections give rise to the same (unparameterised) geodesics. A brief review of some relevant recent work is provided and a list…

Differential Geometry · Mathematics 2009-08-12 Graham S. Hall , David P. Lonie

We give a complete list of mutually non-diffeomorphic normal forms for the two-dimensional metrics that admit one essential (i.e., non-homothetic) projective vector field. This revises a result from the literature and extends the results of…

Differential Geometry · Mathematics 2020-02-20 Gianni Manno , Andreas Vollmer

We show that on a Kahler manifold whether the J-flow converges or not is independent of the chosen background metric in its Kahler class. On toric manifolds we give a numerical characterization of when the J-flow converges, verifying a…

Differential Geometry · Mathematics 2014-12-17 Tristan C. Collins , Gábor Székelyhidi

Any oriented 4-dimensional real vector bundle is naturally a line bundle over a bundle of quaternion algebras. In this paper we give an account of modules over bundles of quaternion algebras, discussing Morita equivalence, characteristic…

Algebraic Topology · Mathematics 2018-11-13 Martin Cadek , Michael Crabb , Jiri Vanzura

In this short note, we prove the Miyaoka-Yau inequality for minimal projective $n$-manifolds of general type by using K\"ahler-Ricci flow.

Differential Geometry · Mathematics 2008-12-04 Yuguang Zhang

In this note we propose to show that the K\"ahler-Ricci flow fits naturally within the context of the Minimal Model Program for projective varieties. In particular we show that the flow detects, in finite time, the contraction theorem of…

Algebraic Geometry · Mathematics 2007-05-23 Paolo Cascini , Gabriele La Nave

We consider timelike and spacelike reductions of 4D, N = 2 Minkowskian and Euclidean vector multiplets coupled to supergravity and the maps induced on the scalar geometry. In particular, we investigate (i) the (standard) spatial c-map, (ii)…

High Energy Physics - Theory · Physics 2015-07-17 Vicente Cortés , Paul Dempster , Thomas Mohaupt , Owen Vaughan

We introduce the notion of K\"ahler manifolds that are almost Einstein and we define a generalized mean curvature vector field along submanifolds in them. We prove that Lagrangian submanifolds remain Lagrangian, when deformed in direction…

Differential Geometry · Mathematics 2011-07-19 Tapio Behrndt

This paper constructs the geometrically natural objects which are associated with any projection tensor field on a manifold with any affine connection. The approaches to projection tensor fields which have been used in general relativity…

General Relativity and Quantum Cosmology · Physics 2009-10-22 Robert H. Gowdy

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

The Wu--Yau theorem asserts that a compact K\"ahler manifold with negative holomorphic sectional curvature admits a cohomologous metric with negative Ricci curvature. We introduce a conjectural positive analog of the Wu--Yau theorem and…

Differential Geometry · Mathematics 2023-06-21 Kyle Broder

We give a complete description of all locally conformally K\"ahler structures with holomorphic Lee vector field on a compact complex manifold of Vaisman type. This provides in particular examples of such structures whose Lee vector field is…

Differential Geometry · Mathematics 2023-05-02 Farid Madani , Andrei Moroianu , Mihaela Pilca

We prove the local classification of K\"ahler metrics with constant holomorphic sectional curvature by exploiting the geometry of the bundle of 1-jets of holomorphic functions.

Differential Geometry · Mathematics 2025-07-30 Martin de Borbon

We classify all complete projective special real manifolds with reducible cubic potential, obtaining four series. For two of the series the manifolds are homogeneous, for the two others the respective automorphism group acts with…

Differential Geometry · Mathematics 2020-03-17 Vicente Cortés , Malte Dyckmanns , Michel Jüngling , David Lindemann