Derivations for the MPS overlap formulas of rational spin chains

Fuente: arXiv
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Main Author: Gombor, Tamas
Format: Preprint
Published: 2025
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author Gombor, Tamas
author_facet Gombor, Tamas
contents We derive a universal formula for the overlaps between integrable matrix product states (MPS) and Bethe eigenstates in $\mathfrak{gl}_{N}$ symmetric spin chains. This formula expresses the normalized overlap as a product of a MPS-independent Gaudin-determinant ratio and a MPS-dependent scalar factor constructed from eigenvalues of commuting operators, defined via the $K$-matrix associated with the MPS. Our proof is fully representation-independent and relies solely on algebraic Bethe Ansatz techniques and the $KT$-relation. We also propose a generalization of the overlap formula to $\mathfrak{so}_{N}$ and $\mathfrak{sp}_{N}$ spin chains, supported by algebra embeddings and low-rank isomorphisms. These results significantly broaden the class of integrable initial states for which exact overlap formulas are available, with implications for quantum quenches and defect CFTs.
format Preprint
id arxiv_https___arxiv_org_abs_2505_20234
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Derivations for the MPS overlap formulas of rational spin chains
Gombor, Tamas
High Energy Physics - Theory
Mathematical Physics
Exactly Solvable and Integrable Systems
We derive a universal formula for the overlaps between integrable matrix product states (MPS) and Bethe eigenstates in $\mathfrak{gl}_{N}$ symmetric spin chains. This formula expresses the normalized overlap as a product of a MPS-independent Gaudin-determinant ratio and a MPS-dependent scalar factor constructed from eigenvalues of commuting operators, defined via the $K$-matrix associated with the MPS. Our proof is fully representation-independent and relies solely on algebraic Bethe Ansatz techniques and the $KT$-relation. We also propose a generalization of the overlap formula to $\mathfrak{so}_{N}$ and $\mathfrak{sp}_{N}$ spin chains, supported by algebra embeddings and low-rank isomorphisms. These results significantly broaden the class of integrable initial states for which exact overlap formulas are available, with implications for quantum quenches and defect CFTs.
title Derivations for the MPS overlap formulas of rational spin chains
topic High Energy Physics - Theory
Mathematical Physics
Exactly Solvable and Integrable Systems
url https://arxiv.org/abs/2505.20234