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Hermitian connection

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In mathematics, a Hermitian connection {\displaystyle \nabla } is a connection on a Hermitian vector bundle E {\displaystyle E} over a smooth manifold M {\displaystyle M} which is compatible with the Hermitian metric , {\displaystyle \langle \cdot ,\cdot \rangle } on E {\displaystyle E} , meaning that

v s , t = v s , t + s , v t {\displaystyle v\langle s,t\rangle =\langle \nabla _{v}s,t\rangle +\langle s,\nabla _{v}t\rangle }

for all smooth vector fields v {\displaystyle v} and all smooth sections s , t {\displaystyle s,t} of E {\displaystyle E} .

If X {\displaystyle X} is a complex manifold, and the Hermitian vector bundle E {\displaystyle E} on X {\displaystyle X} is equipped with a holomorphic structure, then there is a unique Hermitian connection whose (0, 1)-part coincides with the Dolbeault operator ¯ E {\displaystyle {\bar {\partial }}_{E}} on E {\displaystyle E} associated to the holomorphic structure. This is called the Chern connection on E {\displaystyle 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 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. ISBN 0-691-08467-X.


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