Chern character and Fermi point

Kyouhei Horie

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arXiv · 2505.06704

Chern character and Fermi point

Kyouhei Horie

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Abstract

This paper expresses the Chern character for topological K-theory based on the formulation of the family of Fredholm operators, by using the points at which the Fredholm operator becomes singular (Fermi points). In particular, we explain that the odd Chern character can be thought of as a generalization of the spectral flow. As applications, we give elementary proofs of the evenness of the edge index and the bulk-edge correspondence for four-dimensional topological insulators with time-reversal symmetry of class AI.

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Kyouhei Horie. 2025-05-10. Chern character and Fermi point. https://arxiv.org/abs/2505.06704

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