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We review basic facts on the structure of nearly K\"ahler manifolds, focussing in particular on the six-dimensional case. A self-contained proof that nearly K\"ahler six-manifolds are Einstein is given by combining different known results.…

Differential Geometry · Mathematics 2020-10-26 Giovanni Russo

In this paper, the theory of space-time in 4-dimensional Kaehler manifold has been studied. We have discussed the Einstein equation with cosmological constant in perfect fluid Kaehler space-time manifold and proved that the isotropic…

General Mathematics · Mathematics 2016-03-24 B. B. Chaturvedi , Pankaj Pandey

A rigidity result for a class of compact generalized quasi-Einstein manifolds with constant scalar curvature is obtained. Moreover, under some geometric assumptions, the rigidity for the noncompact case is also proved. Considering non…

Differential Geometry · Mathematics 2021-12-09 Antonio Airton Freitas Filho , Keti Tenenblat

The main result is that the qc-scalar curvature of a seven dimensional quaternionic contact Einstein manifold is a constant. In addition, we characterize qc-Einstein structures with certain flat vertical connection and develop their local…

Differential Geometry · Mathematics 2013-06-04 S. Ivanov , I. Minchev , D. Vassilev

A simple geometric procedure is proposed for constructing Wick symbols on cotangent bundles to Riemannian manifolds. The main ingredient of the construction is a method of endowing the cotangent bundle with a formal K\"ahler structure. The…

High Energy Physics - Theory · Physics 2009-11-10 I. V. Gorbunov , S. L. Lyakhovich , A. A. Sharapov

The object of the present paper is to study some properties of para-K$\"{a}$hler manifold whose metric is conformal Einstein soliton. We have studied some certain curvature properties of para-K$\"{a}$hler manifold admitting conformal…

Differential Geometry · Mathematics 2020-05-13 Soumendu Roy , Santu Dey , Arindam Bhattacharyya

We study locally conformal calibrated $G_2$-structures whose underlying Riemannian metric is Einstein, showing that in the compact case the scalar curvature cannot be positive. As a consequence, a compact homogeneous $7$-manifold cannot…

Differential Geometry · Mathematics 2020-08-11 Anna Fino , Alberto Raffero

We are concerned in this article with a classical topic in spectral geometry dating back to McKean-Singer, Patodi and Tanno: whether or not the constancy of sectional curvature (resp. holomorphic sectional curvature) of a compact Riemannian…

Differential Geometry · Mathematics 2023-12-13 Ping Li , Xiaomei Sun , Anqiang Zhu

We study the class of non-degenerate homogeneous structures of linear type in the pseudo-K\"ahler, para-K\"ahler, pseudo-quaternion K\"ahler and para-quaternion K\"ahler cases. We show that these structures characterize spaces of constant…

Differential Geometry · Mathematics 2013-11-14 Ignacio Luján , Andrew Swann

We prove that any Kaehler manifold admitting a flat complex conformal connection is a Bochner-Kaehler manifold with special scalar distribution and zero geometric constants. Applying the local structural theorem for such manifolds we obtain…

Differential Geometry · Mathematics 2007-06-07 Georgi Ganchev , Vesselka Mihova

We produce new examples of non-K\"ahler complete expanding gradient Ricci solitons on trivial vector bundles over a product of Einstein manifolds with positive scalar curvature.

Differential Geometry · Mathematics 2008-11-25 Andrew S. Dancer , McKenzie Y. Wang

This paper concerns the explicit construction of extremal Kaehler metrics on total spaces of projective bundles, which have been studied in many places. We present a unified approach, motivated by the theory of hamiltonian 2-forms (as…

Differential Geometry · Mathematics 2015-06-26 Vestislav Apostolov , David M. J. Calderbank , Paul Gauduchon , Christina W. Tonnesen-Friedman

Firstly we give a condition to split off the K"ahler factor from a nearly pseudo-K"ahler manifold and apply this to get a structure result in dimension 8. Secondly we extend the construction of nearly K"ahler manifolds from twistor spaces…

Differential Geometry · Mathematics 2009-12-18 Lars Schäfer

It is well-known that every 6-dimensional strictly nearly K\"{a}hler manifold $(M,g,J)$ is Einstein with positive scalar curvature $scal>0$. Moreover, one can show that the space $E$ of co-closed primitive (1,1)-forms on $M$ is stable under…

Differential Geometry · Mathematics 2011-02-22 Andrei Moroianu , Uwe Semmelmann

We show that the unit tangent bundle of S^4 and a real cohomology CP^3 admit Riemannian metrics with positive sectional curvature almost everywhere. These are the only examples so far with positive curvature almost everywhere that are not…

Differential Geometry · Mathematics 2014-11-11 Peter Petersen , Frederick Wilhelm

Constructing a classical mechanical system associated with a given quantum mechanical one, entails construction of a classical phase space and a corresponding Hamiltonian function from the available quantum structures and a notion of…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Ghanashyam Date

In this article we study compact K\ahler manifolds satisfying a certain nonnegativity condition on the bisectional curvature. Under this condition, we show that the scalar curvature is nonnegative and that the first Chern class is positive…

Differential Geometry · Mathematics 2011-09-01 Albert Chau , Luen-Fai Tam

The authors give a short survey of previous results on $\delta$-homogeneous Riemannian manifolds, forming a new proper subclass of geodesic orbit spaces with non-negative sectional curvature, which properly includes the class of all normal…

Differential Geometry · Mathematics 2009-03-04 V. N. Berestovskii , E. V. Nikitenko , Yu. G. Nikonorov

In this paper, we show that every harmonic map from a compact K\"ahler manifold with uniformly RC-positive curvature to a Riemannian manifold with non-positive complex sectional curvature is constant. In particular, there is no non-constant…

Differential Geometry · Mathematics 2018-09-13 Jun Wang , Xiaokui Yang

In this paper, we deduce a Bochner-type identity for compact gradient Einstein-type manifolds with boundary. As consequence, we are able to show a rigidity result for Einstein-type manifolds assuming the parallel Ricci curvature condition.…

Differential Geometry · Mathematics 2024-03-06 Maria Andrade , Halyson Baltazar , Christopher Queiroz