Hidden Bose-Einstein Singularities in Correlated Electron Systems: II. Pseudogap Phase in the Weakly Attractive Hubbard Model
Fuente:
arXiv
Saved in:
| Main Author: | |
|---|---|
| Format: | Preprint |
| Published: |
2025
|
| Subjects: | |
| Online Access: | |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866912470939992064 |
|---|---|
| author | Kita, Takafumi |
| author_facet | Kita, Takafumi |
| contents | The hidden Bose-Einstein singularities of correlated electron systems, whose possible existence has been pointed out in a previous paper based on quantum field theory of ordered phases [T. Kita, J. Phys. Soc. Jpn. {\bf 93}, 124704 (2024)], are studied in more detail in terms of the attractive Hubbard model, for which the mean-field theory predicts that spin-singlet superconductivity is realized at low enough temperatures for any band structure and interaction strength. It is shown that incorporating correlation effects should change the mean-field superconducting solution substantially and qualitatively even in the weak coupling, implying that the system lies in the strong-coupling region perturbatively. The hidden singularity is found to be present around the mean-field superconducting temperature $T_{{\rm c}0}$, below which the standard self-consistent treatment by quantum field theory cannot be used due to divergences in the zero Matsubara frequency branch obeying Bose-Einstein statistics. Our method to recover the applicability with a Lagrange multiplier predicts that the singularity is a physical entity signaling the threshold of a pseudogap phase with a characteristic V-shape structure in the density of states near zero energy, which lies above the superconducting phase and originates from the emerging one-particle-reducible structure in the self-energy. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2505_09910 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Hidden Bose-Einstein Singularities in Correlated Electron Systems: II. Pseudogap Phase in the Weakly Attractive Hubbard Model Kita, Takafumi Strongly Correlated Electrons Quantum Gases Statistical Mechanics Superconductivity The hidden Bose-Einstein singularities of correlated electron systems, whose possible existence has been pointed out in a previous paper based on quantum field theory of ordered phases [T. Kita, J. Phys. Soc. Jpn. {\bf 93}, 124704 (2024)], are studied in more detail in terms of the attractive Hubbard model, for which the mean-field theory predicts that spin-singlet superconductivity is realized at low enough temperatures for any band structure and interaction strength. It is shown that incorporating correlation effects should change the mean-field superconducting solution substantially and qualitatively even in the weak coupling, implying that the system lies in the strong-coupling region perturbatively. The hidden singularity is found to be present around the mean-field superconducting temperature $T_{{\rm c}0}$, below which the standard self-consistent treatment by quantum field theory cannot be used due to divergences in the zero Matsubara frequency branch obeying Bose-Einstein statistics. Our method to recover the applicability with a Lagrange multiplier predicts that the singularity is a physical entity signaling the threshold of a pseudogap phase with a characteristic V-shape structure in the density of states near zero energy, which lies above the superconducting phase and originates from the emerging one-particle-reducible structure in the self-energy. |
| title | Hidden Bose-Einstein Singularities in Correlated Electron Systems: II. Pseudogap Phase in the Weakly Attractive Hubbard Model |
| topic | Strongly Correlated Electrons Quantum Gases Statistical Mechanics Superconductivity |
| url | https://arxiv.org/abs/2505.09910 |