We prove the classical Yano-Obata conjecture by showing that the connected component of the group of holomorph-projective transformations of a closed, connected Riemannian Kähler manifold consists of isometries unless the metric has constant positive holomorphic curvature.
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Integral foliated simplicial volume vanishes for manifolds with -action.
Study local diffeomorphisms of conformal circles in pseudo-Riemannian manifolds.
The integrability conditions for the existence of a conformal Killing-Yano tensor of arbitrary order are worked out in all dimensions and expressed in terms of the Weyl tensor. As a consequence, the integrability conditions for the existence of a Killing-Yano tensor are also obtained. By means of such conditions, it is…
Killing-Yano and conformal Killing-Yano superalgebras are rigid in constant curvature manifolds.
We provide a generalization of the Lie algebra of conformal Killing vector fields to conformal Killing-Yano forms. A new Lie bracket for conformal Killing-Yano forms that corresponds to slightly modified Schouten-Nijenhuis bracket of differential forms is proposed. We show that conformal Killing-Yano forms satisfy a gr…
Two Kähler metrics on a complex manifold are called c-projectively equivalent if their -planar curves coincide. These curves are defined by the property that the acceleration is complex proportional to the velocity. We give an explicit local description of all pairs of c-projectively equivalent Kähler metrics of arb…
Study Minkowski formula for conformal Killing-Yano 2-forms in constant curvature spacetimes.
Study finds only complex 2-step nilpotent Lie groups have Killing-Yano forms.
New currents derived from Killing-Yano tensors for gravity.
The integrability conditions for the existence of Killing-Yano tensors or, equivalently, covariantly closed conformal Killing-Yano tensors, in the presence of torsion are worked out. As an application, all metrics and torsions compatible with the existence of a Killing-Yano tensor of order n-1 are obtained. Finally, th…
The study classifies special flows on specific geometric groups.
The properties of a Killing-Yano tensor of order n-1 in an n-dimensional manifold are investigated. The integrability conditions are worked out and all metrics admitting a Killing-Yano tensor of order n-1 are found. It is pointed out a connection between such tensors and a generalization of the concept of angular momen…
We show that the Euclidean Kerr-NUT-(A)dS metric in dimensions locally admits hermitian complex structures. These are derived from the existence of a non-degenerate closed conformal Killing-Yano tensor with distinct eigenvalues. More generally, a conformal Killing-Yano tensor, provided its exterior derivativ…
We show the existence of conformal Killing-Yano tensors on a manifold endowed with a mixed 3-Sasakian structure.
Harmonic spinors linked to twistor spinors via potential forms and conformal Killing-Yano forms.
We show that the first-order symmetry operators of twistor spinors can be constructed from conformal Killing-Yano forms in conformally-flat backgrounds. We express the conditions on conformal Killing-Yano forms to obtain mutually commuting symmetry operators of twistor spinors. Conformal superalgebras which consist of …
Extended supersymmetry leads to Yano F structures on a manifold.
We give a rigorous geometric proof of the Murakami-Yano formula for the volume of a hyperbolic tetrahedron. In doing so, we are led to consider generalized hyperbolic tetrahedra, which are allowed to be non-convex, and have vertices `beyond infinity'; and we uncover a group, which we call 22.5K, of 23040 scissors-class…
Researchers derive symmetry operators from twistor spinors in curved spacetime.
The role of Killing and Killing-Yano tensors for studying the geodesic motion of the particle and the superparticle in a curved background is reviewed. Additionally the Papadopoulos list [74] for Killing-Yano tensors in G structures is reproduced by studying the torsion types these structures admit. The Papadopoulos li…
Generically, the set of points along which two non-singular vector fields on the three-sphere are positively (resp. negatively) collinear form a link. We prove that the two vector fields are homotopic if and only if the linking number of those links is zero. We use this criterion to give a new proof of a result of Yano…
Estimates quasi-local mass using Minkowski formula and conformal Killing-Yano forms.
In the first part of this paper, we consider smooth maps from a compact orientable 3-manifold without boundary to the 2-sphere. We give a geometric criterion to decide whether two given maps are homotopic, based on the sets of points where the maps are equal or antipodal. We extend this criterion to non-singular vector…
A generalized hyperbolic tetrahedra is a polyhedron (possibly non-compact) with finite volume in hyperbolic space, obtained from a tetrahedron by the polar truncation at the vertices lying outside the space. In this paper it is proved that a volume formula for ordinary hyperbolic tetrahedra devised by J. Murakami and M…
Study shows complex affine transformations index is at most 2 for Kähler manifolds.
Study BGG operators on homogeneous conformal geometries.
The study generalizes twistor spinors to Kähler manifolds and finds bilinear form equations.
Researchers describe a method to construct Ricci-flat metrics on a specific surface.
This paper reviews golden Riemannian manifolds over the past decade.
The higher-dimensional Kerr-NUT-de Sitter spacetime describes the general rotating asymptotically de Sitter black hole with NUT parameters. It is known that such a spacetime possesses a rank-2 closed conformal Killing-Yano (CKY) tensor as a ``hidden'' symmetry which provides the separation of variables for the geodesic…
The paper proves Liouville-type theorems on Hadamard manifolds.
Survey of weak metric f-manifolds, generalizing K. Yano's structures.
New formulation of Schrödinger connections preserves vector lengths in geometry.
Extends symmetry superalgebras to include all hidden symmetries of manifolds.
New definitions and properties of harmonic vector fields on Finsler manifolds.
It has been shown that for each Killing-Yano (KY)-form accepted by an -dimensional (pseudo)Riemannian manifold of arbitrary signature, two basic gravitational currents can be defined. Conservation of the currents are explicitly proved by showing co-exactness of the one and co-closedness of the other. Some general ge…
New structures defined for studying contact foliations and their geometry.
Study invariant CKY 2-forms on 5D Lie groups, classifying and determining their properties.
Study finds all hyper-Kähler 4-manifolds with specific symmetries and structures.
Extended superalgebras from twistor and Killing spinors in constant curvature and Einstein manifolds.
We construct some lift of an almost complex structure to the cotangent bundle, using a connection on the base manifold. This generalizes the complete lift defined by I.Sato and the horizontal lift introduced by K.Yano and S.Ishihara. We study some geometric properties of this lift and its compatibility with symplectic …
We abstract Morimoto's construction of complex structures on product manifolds to pairs of certain generalized -structures on manifolds that are not necessarily global products. As applications we characterize invariant generalized complex structures on product manifolds in which one factor is a Lie group and we gen…
The present paper regards the volume function of a doubly truncated hyperbolic tetrahedron. Starting from the previous results of J. Murakami, U. Yano and A. Ushijima, we have developed a unified approach to express the volume in different geometric cases via dilogarithm functions and to treat properly the many analyti…
Families of linear connections are constructed on almost contact manifolds with Norden metric. An analogous connection to the symmetric Yano connection is obtained on a normal almost contact manifold with Norden metric and closed structural 1-form. The curvature properties of this connection are studied on two basic cl…
We classify all spacetimes with a closed rank-2 conformal Killing-Yano tensor. They give a generalization of Kerr-NUT-de Sitter spacetimes. The Einstein condition is explicitly solved and written as an indefinite integral. It is characterized by a polynomial in the integrand. We briefly discuss the smoothness condition…
The study proves that conformal Killing vector fields on manifolds with positive Ricci curvature are non-trivial.
A generalization to the almost complex setting of a well-known result by S. Webster is given. Namely, we prove that if is a strongly pseudoconvex hypersurface in an almost complex manifold , then the conormal bundle of is a totally real submanifold of $(T^*M, \J)$, where $\J$ is the lifted almost comple…