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In this document we present a twistor correspondence for half-flat almost-Grassmannian structures on real and complex manifolds. We provide foundational results regarding local theory in the complex setting and a global correspondence when…

Differential Geometry · Mathematics 2023-04-18 Matthew Lam

We introduce slant Riemannian maps from Riemannian manifolds to almost Hermitian manifolds as a generalization of slant immersions, invariant Riemannian maps and anti-invariant Riemannian maps. We give examples, obtain characterizations and…

Differential Geometry · Mathematics 2012-06-18 Bayram Sahin

In this paper we investigate the space of harmonic maps from a 2-torus to $\mathbb{S}^3$ using the spectral curve correspondence and Whitham deformations. In an open and dense subset of a parameter space we find that the space of harmonic…

Differential Geometry · Mathematics 2019-07-26 Emma Carberry , Ross Ogilvie

In contrast to the classical twistor spaces whose fibres are 2-spheres, we introduce twistor spaces over manifolds with almost quaternionic structures of the second kind in the sense of P. Libermann whose fibres are hyperbolic planes. We…

Differential Geometry · Mathematics 2007-05-23 D. E. Blair , J. Davidov , O. Mushkarov

We study the relations between the projective and the almost conformally symplectic structures on a smooth even dimensional manifold. We describe these relations by a single almost conformally symplectic connection with totally trace--free…

Differential Geometry · Mathematics 2017-10-17 Jan Gregorovič

We consider equitorsion second type almost geodesic mappings of a non-symmetric affine connection space in this article. Using different computational methods, we obtained some invariants of these mappings. Last generalized Thomas…

Differential Geometry · Mathematics 2016-09-29 Nenad O. Vesic

We show that given a harmonic map $\varphi$ from a Riemann surface to a classical compact simply connected inner symmetric space, there is a $J_2$-holomorphic twistor lift of $\varphi$ (or its negative) if and only if it is nilconformal. In…

Differential Geometry · Mathematics 2013-11-26 Martin Svensson , John C. Wood

Given a parabolic geometry on a smooth manifold $M$, we study a natural affine bundle $A \to M$, whose smooth sections can be identified with Weyl structures for the geometry. We show that the initial parabolic geometry defines a reductive…

Differential Geometry · Mathematics 2024-10-14 Andreas Cap , Thomas Mettler

Vasiliev equations facilitate globally defined formulations of higher-spin gravity in various correspondence spaces associated with different phases of the theory. In the four-dimensional case this induces a map from a generally covariant…

High Energy Physics - Theory · Physics 2015-05-20 Nicolo Colombo , Per Sundell

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

Weyl fermions are one of the simplest objects that link ideas in geometry and topology to highenergy physics and condensed matter physics. Although the existence of Weyl fermions as elementary particles remains dubious, there is mounting…

Mesoscale and Nanoscale Physics · Physics 2024-06-05 Azaz Ahmad , Gautham Varma K. , Gargee Sharma

Twistor forms are a natural generalization of conformal vector fields on Riemannian manifolds. They are defined as sections in the kernel of a conformally invariant first order differential operator. We study twistor forms on compact…

Differential Geometry · Mathematics 2019-01-08 Andrei Moroianu , Uwe Semmelmann

We consider complete nearly K\"ahler manifolds with the canonical Hermitian connection. We prove some metric properties of strict nearly K\"ahler manifolds and give a sufficient condition for the reducibility of the canonical Hermitian…

Differential Geometry · Mathematics 2007-05-23 Paul-Andi Nagy

Weyl fermions are massless chiral quasiparticles existing in materials known as Weyl semimetals. Topological surface states, associated with the unusual electronic structure in the Weyl semimetals, have been recently demonstrated in linear…

Optics · Physics 2018-04-18 Ce Shang , Yuanlin Zheng , Boris A. Malomed

We introduce the class of almost symmetric submanifolds of Euclidean space, a close relative of symmetric submanifolds and (contact) sub-Riemannian symmetric spaces. More specifically, we prove that every full irreducible almost symmetric…

Differential Geometry · Mathematics 2025-12-18 Claudio Gorodski , Carlos Olmos

We describe some general constructions on a real smooth projective 4-quadric which provide analogues of the Willmore functional and conformal Gauss map in both Lie sphere and projective differential geometry. Extrema of these functionals…

Differential Geometry · Mathematics 2007-05-23 F. E. Burstall , U. Hertrich-Jeromin

We consider the reduced twistor space $Z$ of an almost Hermitian manifold $M$, after O'Brian and Rawnsley (Ann. Global Anal. Geom., 1985). We concentrate on dimension 6. This space has a natural almost complex structure $\mathcal J$…

Differential Geometry · Mathematics 2007-05-23 Jean-Baptiste Butruille

We study the space of (orthogonal) almost complex structures on closed six-dimensional manifolds as the space of sections of the twistor space for a given metric. For a connected six-manifold with vanishing first Betti number, we express…

Differential Geometry · Mathematics 2022-12-05 Gustavo Granja , Aleksandar Milivojević

We construct infinitely many Einstein-Weyl structures on $S^2 \times R$ of signature (-++) which is sufficiently close to the model case of constant curvature, and whose space-like geodesics are all closed. Such structures are obtained from…

Differential Geometry · Mathematics 2009-11-13 Fuminori Nakata

This is a survey on quaternion Hermitian Weyl (locally conformally quaternion K\"ahler) and hyperhermitian Weyl (locally conformally hyperk\"ahler) manifolds. These geometries appear by requesting the compatibility of some quaternion…

Differential Geometry · Mathematics 2007-05-23 Liviu Ornea