Fingerprints of preformed pairs in two-electron angle-resolved photoemission spectroscopy

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Hauptverfasser: Bonča, Janez, Damascelli, Andrea, Berciu, Mona
Format: Preprint
Veröffentlicht: 2026
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author Bonča, Janez
Damascelli, Andrea
Berciu, Mona
author_facet Bonča, Janez
Damascelli, Andrea
Berciu, Mona
contents We use variational exact diagonalization (VED) to calculate the two-electron removal spectral weight for the Hubbard-Holstein model, starting from the ground-state with two electrons on a one-dimensional chain. We argue that this spectral weight provides a valuable proxy for the intensity of 2eARPES processes. Our results show that when contrasted to the presumably larger signal due to two electrons ejected from two different pairs, the presumably weaker signal due to two electrons ejected from the same pair (i) is segregated in energy, appearing at a lower binding energy, and (ii) has a very characteristic momentum dependence, with a different symmetry than that of the signal corresponding to two electrons emitted from two different pairs. We verify that these fingerprints appear for pairs with different symmetries, and prove that they arise as a direct consequence of momentum and energy conservation, therefore they are generic for any model with electron-boson coupling that can lead to formation of electron pairs. Experimental observation of these fingerprints will confirm the existence of pairs. Moreover, the momentum dependence map allows one to distinguish whether the pairs are coherent (superconducting) or not. Finally, we argue that these considerations generalize to finite but low electron concentrations, finite temperatures and higher dimensions.
format Preprint
id arxiv_https___arxiv_org_abs_2604_18560
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Fingerprints of preformed pairs in two-electron angle-resolved photoemission spectroscopy
Bonča, Janez
Damascelli, Andrea
Berciu, Mona
Strongly Correlated Electrons
Superconductivity
We use variational exact diagonalization (VED) to calculate the two-electron removal spectral weight for the Hubbard-Holstein model, starting from the ground-state with two electrons on a one-dimensional chain. We argue that this spectral weight provides a valuable proxy for the intensity of 2eARPES processes. Our results show that when contrasted to the presumably larger signal due to two electrons ejected from two different pairs, the presumably weaker signal due to two electrons ejected from the same pair (i) is segregated in energy, appearing at a lower binding energy, and (ii) has a very characteristic momentum dependence, with a different symmetry than that of the signal corresponding to two electrons emitted from two different pairs. We verify that these fingerprints appear for pairs with different symmetries, and prove that they arise as a direct consequence of momentum and energy conservation, therefore they are generic for any model with electron-boson coupling that can lead to formation of electron pairs. Experimental observation of these fingerprints will confirm the existence of pairs. Moreover, the momentum dependence map allows one to distinguish whether the pairs are coherent (superconducting) or not. Finally, we argue that these considerations generalize to finite but low electron concentrations, finite temperatures and higher dimensions.
title Fingerprints of preformed pairs in two-electron angle-resolved photoemission spectroscopy
topic Strongly Correlated Electrons
Superconductivity
url https://arxiv.org/abs/2604.18560