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arXiv · 2004.11371

Threshold singularities in the XXZ- spin chain

A. A. Ovchinnikov
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Abstract

We calculate the critical exponents of the threshold singularity for the spectral density of the XXZ- spin chain at zero magnetic field for the lower threshold. We show that the corresponding phase shifts are momentum-independent and coinside with the predictions of the effective mobile impurity Hamiltonian approach. We show that for the eigenstates with the high-energy particle with the momentum $k$ which is much larger than the momenta of the particle-hole excitations the formfactor is not described in the framework of the Luttinger model even in the limit $k<<p_F$ but should be evaluated in the framework of the effective mobile impurity Hamiltonian approach.

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BibTeXRIS

A. A. Ovchinnikov. 2020-04-23. Threshold singularities in the XXZ- spin chain. https://doi.org/10.1142/s0217984921500445

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