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48 results for complexified orbits

Study on Hermitian Calabi functional in complexified orbits of symplectic manifolds.

problem Analyzing the Hermitian Calabi functional on complexified orbits of symplectic manifolds.
method Explicit formula for Hessian of Hermitian Calabi functional, semi-positive definiteness proof, and weak parabolicity of Hermitian Calabi flow.
result Hessian of Hermitian Calabi functional is semi-positive definite on complexified orbits.

We first investigate the geometry of orbits of the isotropy action on a semi-simple pseudo-Riemannian symmetric space by investigating the complexified action. Next we investigate the geometry of the orbits of Hermann type actions on the symmetric spaces. By considering two special Hermann type actions on the symmetric…

2008-07-10abs ↗pdf ↗

Study of complexified Hermitian symmetric spaces and their structures.

problem Understanding the hyperkähler structures and symplectic properties of complexified Hermitian symmetric spaces.
method Explicit diffeomorphisms and moment-critical subsets analysis.
result Almost all complex and symplectic structures are equivalent to the ones on G/KG/K and $T^*\left(G_u/K_0 ight)$ respectively.

Representations of CC^*-algebras are realized on section spaces of holomorphic homogeneous vector bundles. The corresponding section spaces are investigated by means of a new notion of reproducing kernel, suitable for dealing with involutive diffeomorphisms defined on the base spaces of the bundles. Applications of th…

2007-07-05abs ↗pdf ↗

Study norm-squared of momentum map in infinite dimensions with applications to symplectic geometry.

problem Understanding the norm-squared of the momentum map in infinite-dimensional settings.
method Calculation of Hessian, decomposition of stabilizer, application to symplectic and complex structures.
result Positive semi-definiteness of Hessian along complexified orbit and new central extensions of symplectomorphism group.

Let M be a Kaehler manifold with a free, holomorphic and Hamiltonian action of the standard n-torus T. We give a simple, explicit and canonical formula for the Kaehler potential on the Kaehler reduction of M. As a consequence we can derive improvements of several classical results known for more general Hamiltonian red…

2003-02-27abs ↗pdf ↗

We prove the K(π,1)K(π,1) conjecture for affine Artin groups: the complexified complement of an affine reflection arrangement is a classifying space. This is a long-standing problem, due to Arnol'd, Pham, and Thom. Our proof is based on recent advancements in the theory of dual Coxeter and Artin groups, as well as on sever…

2019-07-26abs ↗pdf ↗

We shall construct a natural Higgs bundle structure on the complexified Kähler cone of a compact Kähler manifold, which can be seen as an analogy of the classical Higgs bundle structure associated to a variation of Hodge structure. In the proof of the flat-ness of our Higgs bundle, we find a commutator identity that ca…

2016-12-07abs ↗pdf ↗

New combinatorial model for Milnor fibration using oriented matroids.

problem Understanding the homotopy type of Milnor fibers of complexified real arrangements.
method Introducing a poset quasi-fibration based on a subdivision of the Salvetti complex and an oriented matroid.
result Homotopy type of Milnor fiber depends only on the combinatorial structure of the oriented matroid.

The paper constructs homotopically non-trivial spheres in complexified spaces.

problem Embedding spheres in complexified spaces defined by hyperplane arrangements.
method Introducing locally consistent systems of half-spaces, embedding a sphere, and computing twisted intersection numbers.
result The constructed sphere is homotopically non-trivial if the half-space system is globally consistent.

Gradient maps of real reductive group actions on manifolds studied.

problem Analyzing gradient maps of real reductive group actions on manifolds.
method Examined gradient maps μpμ_{\mathfrak{p}} on submanifolds XX of ZZ.
result Gradient flow of ff has a unique limit and critical points in the same orbit belong to the same KK-orbit.

For a real oriented hyperplane arrangement, we show that the corresponding Salvetti complex is homotopy equivalent to the complement of the complexified arrangement. This result was originally proved by M. Salvetti. Our proof follows the framework of a proof given by L. Paris and relies heavily on the notation of orien…

2009-05-27abs ↗pdf ↗

We study the space of conformal immersions of a 2-torus into the 4-sphere. The moduli space of generalized Darboux transforms of such an immersed torus has the structure of a Riemann surface, the spectral curve. This Riemann surface arises as the zero locus of the determinant of a holomorphic family of Dirac type opera…

2007-12-14abs ↗pdf ↗

Let VV be a finite dimensional complex vector space and $W\subseteq \GL(V)$ be a finite complex reflection group. Let $V^{\reg}$ be the complement in VV of the reflecting hyperplanes. We prove that $V^{\reg}$ is a K(π,1)K(π,1) space. This was predicted by a classical conjecture, originally stated by Brieskorn for complex…

2006-10-26abs ↗pdf ↗

Subharmonicity of Dirichlet energy proven for Kähler manifolds.

problem Subharmonicity of Dirichlet energy in Kähler families.
method Polarized family of compact Kähler manifolds, pluriharmonic maps, nonpositive complexified sectional curvature.
result Dirichlet energy is subharmonic in the parameter space.

Criterion for polystability in Lie group actions on manifolds.

problem Characterizing orbits intersecting a specific set in Lie group actions.
method Hilbert-Mumford criterion applied to polystability, using Cartan decomposition and gradient maps.
result Characterization of orbits intersecting a specific set in terms of maximal weight functions.

Let VV be a finite dimensional complex vector space and $W\subset \GL(V)$ be a finite complex reflection group. Let $V^{\reg}$ be the complement in VV of the reflecting hyperplanes. A classical conjecture predicts that $V^{\reg}$ is a K(pi,1)K(pi,1) space. When WW is a complexified real reflection group, the conjecture f…

2004-11-29abs ↗pdf ↗

Reconstructs supersymmetry and supergravity in complexified Z/2-graded Algebraic Geometry.

problem Lack of a precise mathematical framework for supersymmetry and supergravity.
method Complexified Z/2-graded C-infinity Algebraic Geometry, with minimal mathematical patches.
result A precise setting for supersymmetry and supergravity, including fermionic D-branes.

We prove the existence of lattice isomorphic line arrangements having π1π_1-equivalent or homotopy-equivalent complements and non homeomorphic embeddings in the complex projective plane. We also provide two explicit examples, one is formed by real-complexified arrangements while the second is not.

2018-01-08abs ↗pdf ↗

Every finite dimensional real representation of a compact real semisimple Lie algebra determines a metric 2-step nilpotent Lie algebra and a corresponding simply connected metric 2-step nilpotent Lie group N. We study the differential geometry of N using representation theory of the complexified complex semisimple Lie …

2008-06-17abs ↗pdf ↗

We represent algebraic curves via commuting matrix polynomials. This allows us to show that the Hilbert scheme of cohomologically stable twisted rational curves of degree dd in P3\P1{\Bbb P}^3\backslash {\Bbb P}^1 is isomorphic to a complexified hyperkähler quotient of an open subset of a vector space by a non-reductive …

2019-03-05abs ↗pdf ↗

Constructs maps from field theories to complexified K-theory and elliptic cohomology.

problem Identifying geometric models for Chern characters in supersymmetric field theories.
method Higher-dimensional generalization of Fei Han's method, involving super moduli spaces and derived geometry.
result Provides evidence for the Stolz--Teichner program and geometric models for Chern characters.

The complexified Z/2{\Bbb Z}/2-graded CC^\infty-Algebraic Geometry aspect of a superspace(-time) X^\widehat{X} in Sec.\,1 of D(14.1) (arXiv:1808.05011 [math.DG]) together with the Spin-Statistics Theorem in Quantum Field Theory, which requires fermionic components of a superfield be anticommuting, lead us to the notion…

2019-02-17abs ↗pdf ↗

We prove that a K-contact Lie group of dimension five or greater is the central extension of a symplectic Lie group by complexifying the Lie algebra and applying a result from complex contact geometry, namely, that, if the adjoint action of the complex Reeb vector field on a complex contact Lie algebra is diagonalizabl…

2010-06-08abs ↗pdf ↗

We identify two Frobenius manifolds obtained from two different differential Gerstenhaber-Batalin-Vilkovisky algebras on a compact Kaehler manifold. One is constructed on the Dolbeault cohomology, and the other on the de Rham cohomology. Our result can be considered as a generalization of the identification of the Dolb…

1998-05-21abs ↗pdf ↗

We present the alternative topological twisting of N=4 Yang-Mills, in which the path integral is dominated not by instantons, but by flat connections of the COMPLEXIFIED gauge group. The theory is nontrivial on compact orientable four-manifolds with nonpositive Euler number, which are necessarily not simply connected. …

1995-06-01abs ↗pdf ↗

This paper describes results characterizing the range of the time-t heat operator on various manifolds, including Euclidean spaces, spheres, and hyperbolic spaces. The guiding principle behind these results is this: The functions in the range of the heat operator should be, roughly, those functions having an analytic c…

2004-09-17abs ↗pdf ↗

Study limits of adjoint orbits for Lie groups, describing nilpotent orbits.

problem Understanding limits of adjoint orbits for Lie groups.
method Systematic and topological study of limits of continuous families of adjoint orbits for non-compact simple Lie groups.
result Explicit description of nilpotent orbits in terms of Richardson orbits for hyperbolic semisimple elements.

For certain problems involving vector fields, it is possible to find an associated imaginary field that, in conjunction with the first, forms a complex field for which the equation can be solved. This result is generalized to arbitrary Clifford algebras, followed by quaternionic vectors as a special case. All results a…

2002-09-28abs ↗pdf ↗

We study Milnor fibers of complexified real line arrangements. We give a new algorithm computing monodromy eigenspaces of the first cohomology. The algorithm is based on the description of minimal CW-complexes homotopic to the complements, and uses the real figure, that is, the adjacency relations of chambers. It enabl…

2013-01-08abs ↗pdf ↗