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48 results for G2(2) structures

G2-manifolds with a cohomogeneity-one action of a compact Lie group G are studied. For G simple, all solutions with holonomy G2 and weak holonomy G2 are classified. The holonomy G2 solutions are necessarily Ricci-flat and there is a one-parameter family with SU(3)-symmetry. The weak holonomy G2 solutions are Einstein o…

2001-11-06abs ↗pdf ↗

Study on G2-structures on solvmanifolds, focusing on Laplacian solitons and Ricci pinching.

problem Existence and interplay of Laplacian solitons and Ricci pinched G2-structures on solvmanifolds.
method Exploration of left-invariant G2-structures on solvable Lie groups, analysis of Ricci pinching properties.
result Obtained Ricci pinching properties and extremal values for G2-structures on solvmanifolds.

We overview the properties of non-infinitesimal deformations of G2-structures on seven-manifolds, and in particular, focus on deformations that lie in the seven-dimensional representation of G2 and are thus defined by a vector. We then consider deformations from G2-structures with the torsion class having one-dimension…

2011-10-20abs ↗pdf ↗

New G2-structures found on Lie groups with strong structural conditions.

problem Existence and structure of extremally Ricci pinched G2-structures on Lie groups.
method Strong structural conditions on Lie algebra, deformation and rigidity studies.
result Three new examples of extremally Ricci pinched G2-structures, all steady Laplacian solitons.

Article explores G2-structures with quadratic conditions, finding new ERP and complete solitons.

problem Investigating closed G2-structures satisfying quadratic conditions.
method Analyzing a second-order PDE system involving parameter λ, producing new examples of ERP and complete solitons.
result First examples of ERP G2-structures, including complete inhomogeneous ERP G2-structure.

Study G2-structures with non-closed four-forms under local conformal conditions.

problem Characterizing G2-structures with non-closed four-forms under local conformal conditions.
method Investigated G2-structures with non-closed four-forms and non-zero Lee form, focusing on Lie algebra properties.
result Found solutions for G2-structures in preposition1 and theorem1.

We give an answer to a question posed recently by R.Bryant, namely we show that a compact 7-dimensional manifold equipped with a G2-structure with closed fundamental form is Einstein if and only if the Riemannian holonomy of the induced metric is contained in G2. This could be considered to be a G2 analogue of the Gold…

2003-06-25abs ↗pdf ↗

Classification of G2-structures on Lie groups with Ricci pinched conditions.

problem Classifying G2-structures on Lie groups under specific geometric conditions.
method Complete classification of left-invariant closed G2-structures on Lie groups, extremally Ricci pinched, up to equivalence and scaling.
result Five distinct G2-structures on five different completely solvable Lie groups, with one unimodular case being exact.

This paper is a review of current developments in the study of moduli spaces of G2 manifolds. G2 manifolds are 7-dimensional manifolds with the exceptional holonomy group G2. Although they are odd-dimensional, in many ways they can be considered as an analogue of Calabi-Yau manifolds in 7 dimensions. They play an impor…

2009-11-11abs ↗pdf ↗

We consider non-infinitesimal deformations of G2-structures on 7-dimensional manifolds and derive an exact expression for the torsion of the deformed G2-structure. We then specialize to a case when the deformation is defined by a vector v and we explicitly derive the expressions for the different torsion components of …

2011-08-11abs ↗pdf ↗

Let M be a G2-manifold. We consider an almost CR-structure on the sphere bundle of unit tangent vectors on M, called the CR twistor space. This CR-structure is integrable if and only if M is a holonomy G2 manifold. We interpret G2-instanton bundles as CR-holomorphic bundles on its twistor space.

2010-03-16abs ↗pdf ↗

We introduce the concept of G2(2)-structure on an orientable 3-manifold M using the setting of generalized geometry of type Bn, study their local deformation by making use of a Moser-type argument, and give a description of the cone of G2(2)-structures.

2013-01-15abs ↗pdf ↗

We give a method to obtain new 7-dimensional Lie algebras endowed with closed and coclosed G2-structures starting from 6-dimensional Lie algebras with symplectic half- at SU(3)-structures and half- at SU(3)- structures, respectively. Finally, we describe all the 7-dimensional Lie algebras with a closed G2-structure tha…

2015-07-27abs ↗pdf ↗

Geodesic concavity and hypersymplectic structures in G2G2-structures space.

problem Analyzing the geodesic concavity and hypersymplectic structures in the space of closed G2G2-structures.
method Utilising the geodesic constructed in the previous article, we show geodesic concavity and decrease in length of G2G2 Laplacian flow.
result Hitchin's volume functional is geodesically concave and the G2G2 Laplacian flow decreases the length.

Let M be a 7-manifold with a G2-structure defined by φ\inΩ^{3}_{+}(M). We prove that φ is conformal-Killing with respect to the associated metric g(φ) if and only if the G2-structure is nearly parallel. Let M be an 8-manifold with a Spin7-structure defined by ψ\inΩ^{4}_{+}(M). We prove that ψ is conformal-Killing with …

2010-06-28abs ↗pdf ↗

We use a G2-structure on a 7-dimensional Riemannian manifold with a fixed metric to define an octonion bundle with a fiberwise non-associative product. We then define a metric-compatible octonion covariant derivative on this bundle that is compatible with the octonion product. The torsion of the G2-structure is then sh…

2015-10-14abs ↗pdf ↗

We classify all seven-dimensional spaces which admit a homogeneous cosymplectic G2-structure. The motivation for this classification is that each of these spaces is a possible principal orbit of a parallel Spin(7)-manifold of cohomogeneity one.

2009-01-06abs ↗pdf ↗

We study the moduli space of SU(3) structure manifolds X that form the internal compact spaces in four-dimensional N=1/2 domain wall solutions of heterotic supergravity with flux. Together with the direction perpendicular to the four-dimensional domain wall, X forms a non-compact 7-manifold Y with torsionful G2 structu…

2014-09-26abs ↗pdf ↗

New formulas for mean curvature of submanifolds in geometries with torsion.

problem Characterizing submanifolds in geometries with intrinsic torsion.
method Deriving formulas for mean curvature of associative, coassociative, and Cayley submanifolds.
result New obstructions to the local existence of coassociative 4-folds in G2-structures with torsion.

This article studies the geometry of moduli spaces of G2-manifolds, associative cycles, coassociative cycles and deformed Donaldson-Thomas bundles. We introduce natural symmetric cubic tensors and differential forms on these moduli spaces. They correspond to Yukawa couplings and correlation functions in M-theory. We ex…

2002-02-06abs ↗pdf ↗

We modify the Laplacian coflow of co-closed G2-structures - ddtψ=Δψ\frac{d}{dt}ψ=Δψ where ψψ is the closed dual 4-form of a G2G_{2}-structure φ\varphi . The modified flow is now parabolic in the direction of closed forms upto diffeomorphisms. We then prove short time existence and uniqueness of solutions to the modified f…

2012-09-19abs ↗pdf ↗

We show how certain diffeomorphism-invariant functionals on differential forms in dimensions 6,7 and 8 generate in a natural way special geometrical structures in these dimensions: metrics of holonomy G2 and Spin(7), metrics with weak holonomy SU(3) and G2, and a new and unexplored example in dimension 8. The general f…

2001-07-13abs ↗pdf ↗

We reduce the embedding problem for hypo SU(2) and SU(3)-structures to the embedding problem for hypo G2-structures into parallel Spin(7)-manifolds. The latter will be described in terms of gauge deformations. This description involves the intrinsic torsion of the initial G2-structure and allows us to prove that the ev…

2009-09-30abs ↗pdf ↗

Researchers compute the ν-invariant for specific G2-structures on nilmanifolds.

problem Detecting connected components of G2-structure moduli spaces.
method Defined and computed the ν-invariant using Mathai-Quillen currents, harmonic spinors, and η-invariants.
result Determined the parity of harmonic spinor dimensions and deduced ν vanishing on invariant spinors.

Study on dimensions of G2-structures on nilmanifolds, proving non-abelian automorphism groups.

problem Dimensions and automorphisms of G2-structures on nilmanifolds.
method Computational analysis of moduli spaces of G2-structures on 7-dimensional nilmanifolds.
result Coclosed G2-structures have non-abelian automorphism groups, unlike closed ones.

Classifies 7D manifolds with specific G2-structures and automorphisms.

problem Classifying 7D manifolds with closed G2-structures and transitive automorphisms.
method Complete classification through detailed analysis of manifold properties and group actions.
result The center of the automorphism group is one-dimensional and the manifold is a product of a flat factor and a homogeneous six-manifold with a specific SU(3)-structure.

Study deformations of G2-instantons on nearly G2 manifolds.

problem Deformations of G2-instantons on nearly G2 manifolds.
method Formulated in terms of spinors and Dirac operators, proved isomorphism of infinitesimal deformations to kernel of an elliptic operator.
result Proved abelian instantons are rigid and described the deformation space of the canonical connection on specific nearly G2 manifolds.

Method to create Einstein SU(3) and G2 structures from specific metrics.

problem Creating Einstein metrics from specific SU(3) and G2 structures.
method Warped products of SU(2) and SU(3) structures on 5 and 6-manifolds with Einstein metrics.
result Different classes of SU(3) and G2 structures can be produced to have an Einstein metric.