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Let G be a connected reductive group. To any irreducible G-variety one associates a certain linear group generated by reflections called the Weyl group. Weyl groups play an important role in the study of embeddings of homogeneous spaces. We…

Algebraic Geometry · Mathematics 2010-06-03 Ivan V. Losev

We review recent developments and applications of the classification of the Weyl tensor in higher dimensional Lorentzian geometries. First, we discuss the general setup, i.e. main definitions and methods for the classification, some…

General Relativity and Quantum Cosmology · Physics 2012-12-17 Marcello Ortaggio , Vojtech Pravda , Alena Pravdova

In this paper, we show that associated to any coisotropic Cartan geometry there is a twisted Courant algebroid. This includes in particular parabolic geometries. Using this twisted Courant structure, we give some new results about the…

Differential Geometry · Mathematics 2018-02-28 Xu Xiaomeng

We introduce the new algebraic property of Weyl compatibility for symmetric tensors and vectors. It is strictly related to Riemann compatibility, which generalizes the Codazzi condition while preserving much of its geometric implications.…

Mathematical Physics · Physics 2016-03-10 Carlo A. Mantica , Luca G. Molinari

We study substructures of the Weyl group of conformal transformations of the metric of (pseudo)Riemannian manifolds. These substructures are identified by differential constraints on the conformal factors of the transformations which are…

High Energy Physics - Theory · Physics 2024-07-10 Riccardo Martini , Gregorio Paci , Dario Sauro , Gian Paolo Vacca , Omar Zanusso

We consider principal fibre bundles with a given connection and construct almost complex structures on the total space if the adjoint bundle is isomorphic to the tangent bundle of the base. We derive the integrability condition. If the…

Differential Geometry · Mathematics 2017-02-15 Raphael Zentner

We construct a trace map on the chiral homology of chiral Weyl algebra for any smooth Riemann surface. Our trace map can be viewed as a chiral version of the deformed HKR quasi-isomorphism. This also provides a mathematical rigorous…

Quantum Algebra · Mathematics 2023-10-24 Zhengping Gui

We introduce a notion of admissible Hermitian metrics on parabolic bundles and define positivity properties for the same. We develop Chern-Weil theory for parabolic bundles and prove that our metric notions coincide with the already…

Differential Geometry · Mathematics 2018-10-15 Indranil Biswas , Vamsi Pritham Pingali

We use the theory of Clifford algebras and Vahlen groups to study Weyl groups of hyperbolic Kac-Moody algebras T_n^{++}, obtained by a process of double extension from a Cartan matrix of finite type T_n, whose corresponding generalized…

Group Theory · Mathematics 2017-05-16 Alex J. Feingold , Daniel Vallières

The aim of this paper and its sequel is to introduce and classify the holonomy algebras of the projective Tractor connection. After a brief historical background, this paper presents and analyses the projective Cartan and Tractor…

Differential Geometry · Mathematics 2007-05-23 Stuart Armstrong

Let $Y_{1},\dots,Y_{l}$ be smooth irreducible projective curves and let $Y$ be its disjoint union. Given a semisimple reductive algebraic group $G$ and a faithful representation $\rho:G\hookrightarrow \textrm{SL}(V)$ we construct a…

Algebraic Geometry · Mathematics 2020-07-28 Ángel Luis Muñoz Castañeda

We introduce a new family of operators in 4-dimensional pseudo-Riemannian manifolds with a non-vanishing Weyl scalar (non-degenerate spaces) that keep the conformal covariance of \emph{conformally covariant tensor concomitants}. A…

Differential Geometry · Mathematics 2024-09-27 Alfonso García-Parrado

The realization of tractor bundles as associated bundles in conformal geometry is studied. It is shown that different natural choices of principal bundle with normal Cartan connection corresponding to a given conformal manifold can give…

Differential Geometry · Mathematics 2012-01-13 C. Robin Graham , Travis Willse

We prove the existence of compact pseudo-Riemannian manifolds with parallel Weyl tensor which are neither conformally flat nor locally symmetric, and represent all indefinite metric signatures in all dimensions $\,n\ge5$. Until now such…

Differential Geometry · Mathematics 2023-10-03 Andrzej Derdzinski , Ivo Terek

We generalize the concept of three-dimensional topological Weyl semimetal to a class of five dimensional (5D) gapless solids, where Weyl points are generalized to Weyl surfaces which are two-dimensional closed manifolds in the momentum…

Mesoscale and Nanoscale Physics · Physics 2016-07-06 Biao Lian , Shou-Cheng Zhang

We consider weighted parallel spinors in Lorentzian Weyl geometry in arbitrary dimensions, choosing the weight such that the integrability condition for the existence of such a spinor, implies the geometry to be Einstein-Weyl. We then use…

General Relativity and Quantum Cosmology · Physics 2011-11-16 P. Meessen , T. Ortín , A. Palomo-Lozano

A general model for geometric structures on differentiable manifolds is obtained by deforming infinitesimal symmetries. Specifically, this model consists of a Lie algebroid, equipped with an affine connection compatible with the Lie…

Differential Geometry · Mathematics 2012-03-07 Anthony D. Blaom

This article is concerned with causal structures, which are defined as a field of tangentially non-degenerate projective hypersurfaces in the projectivized tangent bundle of a manifold. The local equivalence problem of causal structures on…

Differential Geometry · Mathematics 2018-08-07 Omid Makhmali

We investigate geometric properties of homogeneous parabolic geometries with generalized symmetries. We show that they can be reduced to a simpler geometric structures and interpret them explicitly. For specific types of parabolic…

Differential Geometry · Mathematics 2016-08-10 Jan Gregorovič , Lenka Zalabová

We study the Jones and Tod correspondence between selfdual conformal 4-manifolds with a conformal vector field and abelian monopoles on Einstein-Weyl 3-manifolds, and prove that invariant complex structures correspond to shear-free geodesic…

Differential Geometry · Mathematics 2009-09-25 David M. J. Calderbank , H. Pedersen