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Let $M$ be a pseudo-Hermitian homogeneous space of finite volume. We show that $M$ is compact and the identity component $G$ of the group of holomorphic isometries of $M$ is compact. If $M$ is simply connected, then even the full group of…

Differential Geometry · Mathematics 2020-06-11 Oliver Baues , Wolfgang Globke , Abdelghani Zeghib

We introduce the notion of \emph{biharmonic almost complex structure} on a compact almost Hermitian manifold and we study its regularity and existence in dimension four. First we show that there always exist smooth energy-minimizing…

Differential Geometry · Mathematics 2020-06-11 Weiyong He

We prove several K\"ahlerness criteria for compact Hermitian surfaces under semi-definiteness assumptions on natural Ricci curvatures of the Strominger-Bismut connection. The key tools for proving these results are explicit identities…

Differential Geometry · Mathematics 2026-05-27 Liangdi Zhang

We investigate the deformation theory of a class of generalized calibrations in Riemannian manifolds for which the tangent bundle has reduced structure group U(n), SU(n), G_2 and Spin(7). For this we use the property of the associated…

Differential Geometry · Mathematics 2016-09-07 J. Gutowski , S. Ivanov , G. Papadopoulos

We construct examples of compact hyperkaehler manifolds with torsion (HKT manifolds) which are not homogeneous and not locally conformal hyperkaehler. Consider a total space T of a tangent bundle over a hyperkaehler manifold M. The manifold…

Differential Geometry · Mathematics 2007-05-23 Misha Verbitsky

In this paper, we consider {\em mixed curvature} $\mathcal{C}_{\alpha,\beta}$ for Hermitian manifolds, which is a convex combination of the first Chern Ricci curvature and holomorphic sectional curvature introduced by Chu-Lee-Tam…

Differential Geometry · Mathematics 2025-01-08 Kai Tang

Under some suitable assumptions Riemannian manifolds $(M, g, H)$ that admit a connection $\hat\nabla$ with torsion a 3-form $H$, which is both closed $d H=0$ and $\hat\nabla$-covariantly constant, are locally isometric to a product $N\times…

Differential Geometry · Mathematics 2026-05-18 Georgios Papadopoulos

In this paper we provide examples of hypercomplex manifolds which do not carry HKT structure. We also prove that the existence of HKT structure is not stable under small deformations. Similarly we provide examples of compact complex…

Differential Geometry · Mathematics 2007-05-23 Anna Fino , Gueo Grantcharov

We study Hermitian metrics whose Bismut connection $\nabla^B$ satisfies the first Bianchi identity in relation to the SKT condition and the parallelism of the torsion of the Bimut connection. We obtain a characterization of complex surfaces…

Differential Geometry · Mathematics 2020-05-12 Anna Fino , Nicoletta Tardini

The class of the hypercomplex pseudo-Hermitian manifolds is considered. The flatness of the considered manifolds with the 3 parallel complex structures is proved. Conformal transformations of the metrics are introduced. The conformal…

Differential Geometry · Mathematics 2012-03-27 Kostadin Gribachev , Mancho Manev , Stancho Dimiev

The study of quasi-K\"ahler Chern-flat almost Hermitian manifolds is strictly related to the study of anti-bi-invariant almost complex Lie algebras. In the present paper we show that quasi-K\"ahler Chern-flat almost Hermitian structures on…

Differential Geometry · Mathematics 2011-01-11 Antonio J. Di Scala , Jorge Lauret , Luigi Vezzoni

On a Riemannian almost product manifold $(M,P,g)$ we consider a linear connection preserving the almost product structure $P$ and the Riemannian metric $g$ and having a totally skew-symmetric torsion. We determine the class of the manifolds…

Differential Geometry · Mathematics 2012-05-08 Dimitar Mekerov , Mancho Manev

We pursuit the research line proposed in \cite{YZ-Gflat} about the classification of Hermitian manifolds whose $s$-Gauduchon connection $\nabla^s =(1-\frac{s}{2})\nabla^c + \frac{s}{2}\nabla^b$ is flat, where $s \in \mathbb{R}$ and…

Differential Geometry · Mathematics 2023-03-31 Luigi Vezzoni , Bo Yang , Fangyang Zheng

Homotopy connectedness theorems for complex submanifolds of homogeneous spaces (sometimes referred to as theorems of Barth-Lefshetz type) have been established by a number of authors. Morse Theory on the space of paths lead to an elegant…

Differential Geometry · Mathematics 2014-09-12 Chaitanya Senapathi

In this paper, we study the existence of various harmonic maps from Hermitian manifolds to Kaehler, Hermitian and Riemannian manifolds respectively. By using refined Bochner formulas on Hermitian (possibly non-Kaehler) manifolds, we derive…

Differential Geometry · Mathematics 2014-03-27 Kefeng Liu , Xiaokui Yang

A Theorem of Kirichenko states that the torsion 3-form of the characteristic connection of a nearly K\"ahler manifold is parallel. On the other side, any almost hermitian manifold of type $\mathrm{G}_1$ admits a unique connection with…

Differential Geometry · Mathematics 2009-11-10 Bogdan Alexandrov , Thomas Friedrich , Nils Schoemann

We consider a closed odd-dimensional oriented manifold $M$ together with an acyclic flat hermitean vector bundle $\cF$. We form the trivial fibre bundle with fibre $M$ over the manifold of all Riemannian metrics on $M$. It has a natural…

dg-ga · Mathematics 2007-05-23 U. Bunke

We present a complete classification of simply-connected pluriclosed manifolds with parallel Bismut torsion, extending previously known results in the literature. Consequently, we also establish a splitting theorem for compact manifolds…

Differential Geometry · Mathematics 2026-04-21 Giuseppe Barbaro , Francesco Pediconi , Nicoletta Tardini

We introduce the concept of Bergman bundle attached to a hermitian manifold X, assuming the manifold X to be compact - although the results are local for a large part. The Bergman bundle is some sort of infinite dimensional very ample…

Complex Variables · Mathematics 2022-02-04 Jean-Pierre Demailly

In this note, we analyze the question of when will a complex nilmanifold have K\"ahler-like Strominger (also known as Bismut), Chern, or Riemannian connection, in the sense that the curvature of the connection obeys all the symmetries of…

Differential Geometry · Mathematics 2022-07-18 Quanting Zhao , Fangyang Zheng