Topological invariant for holographic Weyl-$\mathrm Z_2$ semimetal

Fuente: arXiv
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Autores principales: Chen, Xiantong, Ji, Xuanting, Sun, Ya-Wen
Formato: Preprint
Publicado: 2025
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author Chen, Xiantong
Ji, Xuanting
Sun, Ya-Wen
author_facet Chen, Xiantong
Ji, Xuanting
Sun, Ya-Wen
contents The occurrence of a topological phase transition can be demonstrated by a direct observation of a change in the topological invariant. For holographic topological semimetals, a topological Hamiltonian method needs to be employed to calculate the topological invariants due to the strong coupling nature of the system. We calculate the topological invariants for the holographic Weyl semimetal and the holographic Weyl-$\mathrm Z_2$ semimetal, which correspond to the chiral charge and the spin-Chern number, respectively. This is achieved by probing fermions within the system and deriving the topological Hamiltonian from the zero-frequency Green's function. In both cases, we have identified an effective band structure characterized by an infinite number of Weyl or $\mathrm Z_2$ nodes, a distinctive feature of holographic systems different from weakly coupled systems. The topological invariants of these nodes are computed numerically and found to be nonzero, thereby confirming the topologically nontrivial nature of these nodes.
format Preprint
id arxiv_https___arxiv_org_abs_2503_12791
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Topological invariant for holographic Weyl-$\mathrm Z_2$ semimetal
Chen, Xiantong
Ji, Xuanting
Sun, Ya-Wen
High Energy Physics - Theory
The occurrence of a topological phase transition can be demonstrated by a direct observation of a change in the topological invariant. For holographic topological semimetals, a topological Hamiltonian method needs to be employed to calculate the topological invariants due to the strong coupling nature of the system. We calculate the topological invariants for the holographic Weyl semimetal and the holographic Weyl-$\mathrm Z_2$ semimetal, which correspond to the chiral charge and the spin-Chern number, respectively. This is achieved by probing fermions within the system and deriving the topological Hamiltonian from the zero-frequency Green's function. In both cases, we have identified an effective band structure characterized by an infinite number of Weyl or $\mathrm Z_2$ nodes, a distinctive feature of holographic systems different from weakly coupled systems. The topological invariants of these nodes are computed numerically and found to be nonzero, thereby confirming the topologically nontrivial nature of these nodes.
title Topological invariant for holographic Weyl-$\mathrm Z_2$ semimetal
topic High Energy Physics - Theory
url https://arxiv.org/abs/2503.12791