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A hypercomplex manifold is by definition a smooth manifold equipped with two anticommuting integrable almost complex structures. For example, every hyperkaehler manifold is canonically hypercomplex (the converse is not true). For every…

alg-geom · Mathematics 2008-02-03 D. Kaledin

Theorems on the existence of vector fields with given sets of Indexes of isolated Singular points are proved for the cases of closed manifolds, pairs of manifolds, manifolds with boundary, and gradient fields. It is proved that, on a…

Dynamical Systems · Mathematics 2007-05-23 A. O. Prishlyak

Let $M$ and $N$ be smooth closed connected aspherical manifolds with good (in the sense of Serre) fundamental groups $G$ and $H$. We show that if $\widehat G\cong \widehat H$, then $M$ and $N$ are cobordant and the signatures of $M$ and $N$…

Group Theory · Mathematics 2026-01-12 Sam Hughes , Andrew Ng

We obtain a generic regularity result for stationary integral $n$-varifolds with only strongly isolated singularities inside $N$-dimensional Riemannian manifolds, in absence of any restriction on the dimension ($n\geq 2$) and codimension.…

Differential Geometry · Mathematics 2025-03-03 Alessandro Carlotto , Yangyang Li , Zhihan Wang

The essentially unique torsionful version of the classical two-component spinor formalisms of Infeld and van der Waerden is presented. All the metric spinors and connecting objects that arise here are formally the same as the ones borne by…

Mathematical Physics · Physics 2015-01-26 J. G. Cardoso

We develop general techniques for computing the fundamental group of the configuration space of $n$ identical particles, possessing a generic internal structure, moving on a manifold $M$. This group generalizes the $n$-string braid group of…

High Energy Physics - Theory · Physics 2009-10-28 Lee Brekke , Michael J. Dugan , Tom D. Imbo

In this paper we study the singularity manifolds of multidimensional strictly dispersing billiards and show that the proof of the Fundamental theorem for dispersing billiards remain valid for a dense set of finitely smooth scatterers.

Dynamical Systems · Mathematics 2007-05-23 Pavel Batchourine

In this paper we study the locus of singular tuples of a complex valued multisymmetric tensor. The main problem that we focus on is: given the set of singular tuples of some general tensor, which are all the tensors that admit those same…

Algebraic Geometry · Mathematics 2022-06-16 Ettore Teixeira Turatti

The spin foam formalism provides transition amplitudes for loop quantum gravity. Important aspects of the dynamics are understood, but many open questions are pressing on. In this paper we address some of them using a twistorial…

General Relativity and Quantum Cosmology · Physics 2015-06-05 Simone Speziale , Wolfgang M. Wieland

We present a classification theorem for closed smooth spin 2-connected 7-manifolds M. This builds on the almost-smooth classification from the first author's thesis. The main additional ingredient is an extension of the Eells-Kuiper…

Geometric Topology · Mathematics 2020-05-12 Diarmuid Crowley , Johannes Nordström

In this paper we use the G-spin theorem to show that the Davis hyperbolic 4-manifold admits harmonic spinors. This is the first example of a closed hyperbolic 4-manifold that admits harmonic spinors. We also explicitly describe the Spinor…

Geometric Topology · Mathematics 2018-03-20 John G. Ratcliffe , Daniel Ruberman , Steven T. Tschantz

We prove that there exist global solutions of the twistor equation on the Fefferman spaces of strictly pseudoconvex spin manifolds of arbitrary dimension and we study their properties.

Differential Geometry · Mathematics 2007-05-23 Helga Baum

The {\it two-fold singularity} has played a significant role in our understanding of uniqueness and stability in piecewise smooth dynamical systems. When a vector field is discontinuous at some hypersurface, it can become tangent to that…

Dynamical Systems · Mathematics 2015-06-04 Mike R. Jeffrey

An axisymmetric space-localized solution of nonlinear electrodynamics is considered as massive charged particle with spin and magnetic moment. The appropriate solution for nonlinear electrodynamics with ring singularity is investigated. In…

Mathematical Physics · Physics 2012-12-18 Alexander A. Chernitskii

We show that on every Spin(7) manifold there always exists a unique linear connection with totally skew-symmetric torsion preserving a nontrivial spinor and the Spin(7) structure. We express its torsion and the Riemannian scalar curvature…

Differential Geometry · Mathematics 2007-05-23 Stefan Ivanov

It is shown that there exist non-singular cubic surfaces in CP^3 containing 5 twistor lines. This is the maximum number of twistor fibres that a non-singular cubic can contain. Cubic surfaces in CP^3 with 5 twistor lines are classified up…

Differential Geometry · Mathematics 2015-06-23 John Armstrong , Massimiliano Povero , Simon Salamon

We examine the moduli spaces of Type~A connections on oriented and unoriented surfaces both with and without torsion in relation to the signature of the associated symmetric Ricci tensor. If the signature of the symmetric Ricci tensor is…

Differential Geometry · Mathematics 2016-08-24 Peter B Gilkey

Following suggestions of Nekrasov and Siegel, a non-minimal set of fields are added to the pure spinor formalism for the superstring. Twisted $\hat c$=3 N=2 generators are then constructed where the pure spinor BRST operator is the…

High Energy Physics - Theory · Physics 2009-11-11 Nathan Berkovits

We review the relation between the "embedding" formalism and spinorial projective space. The latter is more convenient when treating spin (and indispensable for supersymmetry), as it maintains manifest conformal symmetry while using…

High Energy Physics - Theory · Physics 2012-05-02 W. Siegel

A twistorial formulation of a particle of arbitrary spin has been constructed. Equations of the twistor formulation are obtained for massive and massless spinning particles. The twistor space of the massive particle is formed by two…

High Energy Physics - Theory · Physics 2007-05-23 S. Fedoruk , V. G. Zima