Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5499951 | Journal of Geometry and Physics | 2017 | 24 Pages |
Abstract
For a two-dimensional compact oriented Riemannian manifold (M,g), and a vector field V on M, the Hopf-Poincaré theorem combined with the Gauss-Bonnet theorem gives the Gauss-Bonnet-Hopf-Poincaré (GBHP) formula : âzâZ(V)indz(V)=12Ïâ«MKdÏ, where Z(V) is the set of zeros of V, indz(V) is the index of V at zâZ(V), and K is the curvature of g. We consider a locally trivial fiber bundle Ï:EâM over a compact oriented two-dimensional manifold M, and a section s of this bundle defined over MâΣ, where Σ is a discrete subset of M called the set of singularities of the section. We assume that the behavior of the section s at the singularities is controlled in the following way: s(MâΣ) coincides with the interior part of a surface SâE with boundary âS, and âS is Ïâ1(Σ). For such sections s we define an index of s at a point of Σ, which generalizes in the natural way the index of zero of a vector field, and then prove that the sum of these indices at the points of Σ can be expressed as an integral over S of a 2-form constructed via a connection in E, thus we obtain a generalization of the GBHP formula. Also we consider branched sections with singularities, define an index of a branched section at a singular point, and find a generalization of the GBHP formula for the branched sections.
Related Topics
Physical Sciences and Engineering
Mathematics
Mathematical Physics
Authors
F.A. Arias, M. Malakhaltsev,