Anomalous Chiral Anomaly in Spin-1 Fermionic Systems

Fuente: arXiv
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Auteurs principaux: Mukherjee, Shantonu, Sharma, Sayantan, Pal, Hridis K.
Format: Preprint
Publié: 2025
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author Mukherjee, Shantonu
Sharma, Sayantan
Pal, Hridis K.
author_facet Mukherjee, Shantonu
Sharma, Sayantan
Pal, Hridis K.
contents Chiral anomaly is a key feature of Lorentz-invariant quantum field theories: in presence of parallel external electric and magnetic fields, the number of massless Weyl fermions of a given chirality is not conserved. In condensed matter, emergent chiral fermions in Weyl semimetals exhibit the same anomaly, directly tied to the topological charge of the Weyl node, ensuring a quantized anomaly coefficient. However, many condensed matter systems break Lorentz symmetry while retaining topological nodes, raising the question of how chiral anomaly manifests in such settings. In this work, we investigate this question in spin-1 fermionic systems and show that the conventional anomaly equation is modified by an additional nontopological contribution, leading to a nonquantized anomaly coefficient. This surprising result arises because spin-1 fermions can be decomposed into 2-flavor Weyl fermions coupled to a Lorentz-breaking, momentum-dependent non-Abelian background potential. The interplay between this potential and external electromagnetic fields generates the extra term in the anomaly equation. Our framework naturally generalizes to other Lorentz-breaking systems beyond the spin-1 case.
format Preprint
id arxiv_https___arxiv_org_abs_2503_16241
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Anomalous Chiral Anomaly in Spin-1 Fermionic Systems
Mukherjee, Shantonu
Sharma, Sayantan
Pal, Hridis K.
Strongly Correlated Electrons
High Energy Physics - Theory
Chiral anomaly is a key feature of Lorentz-invariant quantum field theories: in presence of parallel external electric and magnetic fields, the number of massless Weyl fermions of a given chirality is not conserved. In condensed matter, emergent chiral fermions in Weyl semimetals exhibit the same anomaly, directly tied to the topological charge of the Weyl node, ensuring a quantized anomaly coefficient. However, many condensed matter systems break Lorentz symmetry while retaining topological nodes, raising the question of how chiral anomaly manifests in such settings. In this work, we investigate this question in spin-1 fermionic systems and show that the conventional anomaly equation is modified by an additional nontopological contribution, leading to a nonquantized anomaly coefficient. This surprising result arises because spin-1 fermions can be decomposed into 2-flavor Weyl fermions coupled to a Lorentz-breaking, momentum-dependent non-Abelian background potential. The interplay between this potential and external electromagnetic fields generates the extra term in the anomaly equation. Our framework naturally generalizes to other Lorentz-breaking systems beyond the spin-1 case.
title Anomalous Chiral Anomaly in Spin-1 Fermionic Systems
topic Strongly Correlated Electrons
High Energy Physics - Theory
url https://arxiv.org/abs/2503.16241