Entanglement asymmetry in the gapped XYZ spin-1/2 chain
Abstract
The entanglement asymmetry measures how strongly a symmetry is broken inside a subsystem. Analytic results at equilibrium have so far covered free theories and, perturbatively, the critical XXZ chain. We compute the Rényi entanglement asymmetries of a large interval in the gapped, U(1)-breaking phase of the interacting XYZ chain. The calculation combines three ingredients. A charged-moment identity, which we prove for fermionic Gaussian and for injective matrix-product ground states, ties the asymmetry to the static susceptibility of the broken charge. A non-conservation sum rule then evaluates the susceptibility from sine-Gordon form factors, its two-kink and one-breather channels providing a lower bound on the universal amplitude. The Baxter--Johnson--Krinsky--McCoy solution supplies the kink mass for different couplings. Infinite-system density-matrix renormalization group simulations built on these masses reproduce the master formula.
Related
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BibTeX
@misc{santana2026entanglement,
title = {{Entanglement asymmetry in the gapped XYZ spin-$\frac12$ chain}},
author = {Felipe Taha Sant'Ana},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2607.25625},
eprint = {2607.25625},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.25625},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Entanglement asymmetry in the gapped XYZ spin-1/2 chain
AU - Felipe Taha Sant'Ana
PY - 2026
DA - 2026/11/02
PB - arXiv
DO - 10.48550/arxiv.2607.25625
UR - https://arxiv.org/abs/2607.25625
AB - The entanglement asymmetry measures how strongly a symmetry is broken inside a subsystem. Analytic results at equilibrium have so far covered free theories and, perturbatively, the critical XXZ chain. We compute the Rényi entanglement asymmetries of a large interval in the gapped, U(1)-breaking phase of the interacting XYZ chain. The calculation combines three ingredients. A charged-moment identity, which we prove for fermionic Gaussian and for injective matrix-product ground states, ties the asymmetry to the static susceptibility of the broken charge. A non-conservation sum rule then evaluates the susceptibility from sine-Gordon form factors, its two-kink and one-breather channels providing a lower bound on the universal amplitude. The Baxter--Johnson--Krinsky--McCoy solution supplies the kink mass for different couplings. Infinite-system density-matrix renormalization group simulations built on these masses reproduce the master formula.
ER -