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Journal ArticleDOI

Dirac-harmonic maps from index theory

TL;DR: In this article, the authors prove existence results for Dirac-harmonic maps using index theoretical tools and prove that the underlying map between the source and target manifolds is a harmonic map.
Abstract: We prove existence results for Dirac-harmonic maps using index theoretical tools. They are mainly interesting if the source manifold has dimension 1 or 2 modulo 8. Our solutions are uncoupled in the sense that the underlying map between the source and target manifolds is a harmonic map.
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TL;DR: In this paper, the authors studied Dirac-harmonic maps from surfaces to manifolds with torsion, motivated from the superstring action considered in theoretical physics, and discussed analytic and geometric properties of such maps and outline an existence result for uncoupled solutions.
Abstract: We study Dirac-harmonic maps from surfaces to manifolds with torsion, which is motivated from the superstring action considered in theoretical physics. We discuss analytic and geometric properties of such maps and outline an existence result for uncoupled solutions.

31 citations


Cites background or result from "Dirac-harmonic maps from index theo..."

  • ...armonic maps have already been obtained. This includes the regularity of solutions [CJLW05], [Zhu09], [WX09] and the energy identity [CJLW05]. In addition, an existence result for uncoupled solutions [AG12], for the boundary value problem [CJW], [CJWZ13] and for a nonlinear version of Dirac-geodesics [Iso12] have been established. A heat flow approach for Dirac-harmonic maps has been studied in [Bra13a],...

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  • ...lution of the Euler-Lagrange equations (3.4) and (3.5) uncoupled, if φis a harmonic map. Using tools from index theory, a general existence result for uncoupled Diracharmonic maps could be derived in [AG12]. Since the index of the twisted Dirac-operator does not change when considering a connection with torsion on φ−1TNthe arguments from [AG12] can also be applied in our case. Thus, let us briefly recall...

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  • ..., where D/Tor 0 ψ∈ Γ(ΣM⊗ φ−1 0 TN), we have to construct for any smooth variation φtof φ0 a smooth variation of ψtsatisfying d dt R Mhψt,D/ Tor t ψti t=0 = 0. This is the same argument as Cor. 5.2 in [AG12]. Note that D/and D/Tor have the same principal symbol and the same index. Hence, this smooth variation can be constructed by assuming that the index α(M,σ,E) is non-trivial, see [AG12], Prop. 8.2 and...

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Journal ArticleDOI
TL;DR: In this paper, the existence of a global weak solution of the heat flow for Dirac-harmonic maps from compact Riemann surfaces with boundary when the energy of the initial map and the L 2 -norm of the boundary values of the spinor are sufficiently small.

30 citations


Cites methods from "Dirac-harmonic maps from index theo..."

  • ...There have been other approaches, such as [18, 7, 2, 4]....

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Journal ArticleDOI
TL;DR: In this article, several geometric and analytic aspects of Dirac-harmonic maps with curvature term from closed Riemannian surfaces were studied, and the curvature terms were analyzed.
Abstract: We study several geometric and analytic aspects of Dirac-harmonic maps with curvature term from closed Riemannian surfaces.

19 citations


Cites background from "Dirac-harmonic maps from index theo..."

  • ...This includes several analytical results [11], [23], [14], [26] and an existence result for uncoupled solutions [2]....

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  • ...In particular, if f = 0, then φ ∈ W 2,p loc for all p ∈ [1, 2) and φ ∈ W 1,q loc for all q ∈ [1,∞)....

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Journal ArticleDOI
Qun Chen1, Jürgen Jost2, Linlin Sun1, Linlin Sun2, Miaomiao Zhu2 
TL;DR: In this paper, the authors introduced the heat flow for Dirac-geodesics and established its long-time existence and an asymptotic property of the global solution.
Abstract: Dirac-geodesics are Dirac-harmonic maps from one dimensional domains. In this paper, we introduce the heat flow for Dirac-geodesics and establish its long-time existence and an asymptotic property of the global solution. We classify Dirac-geodesics on the standard 2-sphere \(S^2(1)\) and the hyperbolic plane \(\mathbb {H}^2\), and derive existence results on topological spheres and hyperbolic surfaces. These solutions constitute new examples of coupled Dirac-harmonic maps (in the sense that the map part is not simply a harmonic map).

17 citations


Cites background from "Dirac-harmonic maps from index theo..."

  • ...These solutions constitute new examples of nontrivially coupled Dirac-harmonic maps; see [14] for an explicit example of coupled Dirac-harmonic map from surfaces and [1;5] for constructions and existence of uncoupled Dirac-harmonic maps (in the sense that the map part is an ordinary harmonic map) from surfaces and high dimensional manifolds; in section 4, we prove the global existence of the Dirac-geodesic flow (Theorem 1....

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Posted Content
TL;DR: The heat flow for Dirac-harmonic maps on Riemannian spin manifolds was introduced by Chen, Jost, Sun, and Zhu as a tool to get a general existence program.
Abstract: The heat flow for Dirac-harmonic maps on Riemannian spin manifolds is a modification of the classical heat flow for harmonic maps by coupling it to a spinor. It was introduced by Chen, Jost, Sun, and Zhu as a tool to get a general existence program for Dirac-harmonic maps. For source manifolds with boundary they obtained short time existence and the existence of a global weak solution was established by Jost, Liu, and Zhu. We prove short time existence of the heat flow for Dirac-harmonic maps on closed manifolds.

15 citations


Cites background from "Dirac-harmonic maps from index theo..."

  • ...Other examples can be found in [18], [3]....

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References
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2,205 citations


"Dirac-harmonic maps from index theo..." refers background or result in this paper

  • ...e the closed target manifold N has non-positive sectional curvature. Then there exists an energy-minimizing (hence harmonic) map in every homotopy class of smooth maps from any closed manifold Minto N[14, 30]. As an application, pick any closed connected Riemannian spin manifold N with non-positive sectional curvature and dimension n≡ 1 (8). Let N′ be any n-dimensional closed Riemannian spin manifold with...

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  • ...s harmonic but this time fb∗TCP2 becomes trivial, hence no non-trivial Dirac-harmonic map can be found using our methods. In an analogous way, existence results for harmonic maps by e.g. EellsSampson [14] (see also [30]) or Y.L. Xin [35] give Dirac-harmonic maps provided the corresponding α-genus does not vanish. We summarize the results in the following two theorems, where we assume all surfaces to b...

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Book
21 Mar 1951
TL;DR: In this paper, a succint introduction to fiber bundles is provided, which includes such topics as differentiable manifolds and covering spaces, and a brief survey of advanced topics, such as homotopy theory and cohomology theory, before using them to study further properties of fibre bundles.
Abstract: Fibre bundles, an integral part of differential geometry, are also important to physics. This text, a succint introduction to fibre bundles, includes such topics as differentiable manifolds and covering spaces. It provides brief surveys of advanced topics, such as homotopy theory and cohomology theory, before using them to study further properties of fibre bundles.

2,126 citations

Book
05 May 1980
TL;DR: The spectral theory of self-adjoint and normal operators on L2(a, b) spaces has been studied in this article, where it has been shown that the existence and completeness of wave operators can be proved.
Abstract: 1 Vector spaces with a scalar product, pre-Hilbert spaces.- 1.1 Sesquilinear forms.- 1.2 Scalar products and norms.- 2 Hilbert spaces.- 2.1 Convergence and completeness.- 2.2 Topological notions.- 3 Orthogonality.- 3.1 The projection theorem.- 3.2 Orthonormal systems and orthonormal bases.- 3.3 Existence of orthonormal bases, dimension of a Hilbert space.- 3.4 Tensor products of Hilbert spaces.- 4 Linear operators and their adjoints.- 4.1 Basic notions.- 4.2 Bounded linear operators and functionals.- 4.3 Isomorphisms, completion.- 4.4 Adjoint operator.- 4.5 The theorem of Banach-Steinhaus, strong and weak convergence.- 4.6 Orthogonal projections, isometric and unitary operators.- 5 Closed linear operators.- 5.1 Closed and closable operators, the closed graph theorem.- 5.2 The fundamentals of spectral theory.- 5.3 Symmetric and self-adjoint operators.- 5.4 Self-adjoint extensions of symmetric operators.- 5.5 Operators defined by sesquilinear forms (Friedrichs' extension).- 5.6 Normal operators.- 6 Special classes of linear operators.- 6.1 Finite rank and compact operators.- 6.2 Hilbert-Schmidt operators and Carleman operators.- 6.3 Matrix operators and integral operators.- 6.4 Differential operators on L2(a, b) with constant coefficients.- 7 The spectral theory of self-adjoint and normal operators.- 7.1 The spectral theorem for compact operators, the spaces Bp (H1H2).- 7.2 Integration with respect to a spectral family.- 7.3 The spectral theorem for self-adjoint operators.- 7.4 Spectra of self-adjoint operators.- 7.5 The spectral theorem for normal operators.- 7.6 One-parameter unitary groups.- 8 Self-adjoint extensions of symmetric operators.- 8.1 Defect indices and Cayley transforms.- 8.2 Construction of self-adjoint extensions.- 8.3 Spectra of self-adjoint extensions of a symmetric operator.- 8.4 Second order ordinary differential operators.- 8.5 Analytic vectors and tensor products of self-adjoint operators.- 9 Perturbation theory for self-adjoint operators.- 9.1 Relatively bounded perturbations.- 9.2 Relatively compact perturbations and the essential spectrum.- 9.3 Strong resolvent convergence.- 10 Differential operators on L2(?m).- 10.1 The Fourier transformation on L2(?m).- 10.2 Sobolev spaces and differential operators on L2(?m) with constant coefficients.- 10.3 Relatively bounded and relatively compact perturbations.- 10.4 Essentially self-adjoint Schrodinger operators.- 10.5 Spectra of Schrodinger operators.- 10.6 Dirac operators.- 11 Scattering theory.- 11.1 Wave operators.- 11.2 The existence and completeness of wave operators.- 11.3 Applications to differential operators on L2(?m).- A.1 Definition of the integral.- A.2 Limit theorems.- A.3 Measurable functions and sets.- A.4 The Fubini-Tonelli theorem.- A.5 The Radon-Nikodym theorem.- References.- Index of symbols.- Author and subject index.

1,346 citations

BookDOI
31 Jan 1951

1,215 citations

Journal ArticleDOI

937 citations


"Dirac-harmonic maps from index theo..." refers background or result in this paper

  • ...One easily verifies that the only parts in [29] using orientation are parts of the introduction, the definition of φ, Lemma 1....

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  • ...In order to facilitate the comparison to [29] we adapt to their notation to a large extend....

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  • ...As already said above, in [29] it is claimed that M should be orientable....

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  • ...of the results of [29] also hold in this non-orientable case....

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  • ...The following theorem can be deduced from the proofs in [29]:...

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