Unitary Connection
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In mathematics, a Hermitian connection \nabla is a connection on a
Hermitian vector bundle In mathematics, a holomorphic vector bundle is a complex vector bundle over a complex manifold such that the total space is a complex manifold and the projection map is holomorphic. Fundamental examples are the holomorphic tangent bundle of a ...
E over a smooth manifold M which is compatible with the
Hermitian metric In mathematics, and more specifically in differential geometry, a Hermitian manifold is the complex analogue of a Riemannian manifold. More precisely, a Hermitian manifold is a complex manifold with a smoothly varying Hermitian inner product on ea ...
\langle \cdot, \cdot \rangle on E, meaning that : v \langle s,t\rangle = \langle \nabla_v s, t \rangle + \langle s, \nabla_v t \rangle for all smooth vector fields v and all smooth sections s,t of E. If X is a
complex manifold In differential geometry and complex geometry, a complex manifold is a manifold with an atlas of charts to the open unit disc in \mathbb^n, such that the transition maps are holomorphic. The term complex manifold is variously used to mean a com ...
, and the Hermitian vector bundle E on X is equipped with a holomorphic structure, then there is a unique Hermitian connection whose (0, 1)-part coincides with the
Dolbeault operator In mathematics, a complex differential form is a differential form on a manifold (usually a complex manifold) which is permitted to have complex number, complex coefficients. Complex forms have broad applications in differential geometry. On comp ...
\bar_E on E associated to the holomorphic structure. This is called the Chern connection on E. The curvature of the Chern connection is a (1, 1)-form. For details, see Hermitian metrics on a holomorphic vector bundle. In particular, if the base manifold is Kähler and the vector bundle is its tangent bundle, then the Chern connection coincides with the
Levi-Civita connection In Riemannian or pseudo Riemannian geometry (in particular the Lorentzian geometry of general relativity), the Levi-Civita connection is the unique affine connection on the tangent bundle of a manifold (i.e. affine connection) that preserves th ...
of the associated Riemannian metric.


References

* Shiing-Shen Chern, ''Complex Manifolds Without Potential Theory''. * Shoshichi Kobayashi, ''Differential geometry of complex vector bundles''. Publications of the Mathematical Society of Japan, 15. ''Princeton University Press, Princeton, NJ'', 1987. xii+305 pp. . Complex manifolds Structures on manifolds Riemannian geometry {{differential-geometry-stub