Topic
Self-energy
About: Self-energy is a research topic. Over the lifetime, 1888 publications have been published within this topic receiving 50611 citations.
Papers published on a yearly basis
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Papers
TL;DR: In this article, the authors present a topological classification of finite-energy, periodic fields and the classical solutions which minimize the action in each topological sector are examined and the effects of instantons can be reliably calculated at sufficiently high temperature.
Abstract: The current understanding of the behavior of quantum chromodynamics at finite temperature is presented. Perturbative methods are used to explore the high-temperature dynamics. At sufficiently high temperatures the plasma of thermal excitations screens all color electric fields and quarks are unconfined. It is believed that the high-temperature theory develops a dynamical mass gap. However in perturbation theory the infrared behavior of magnetic fluctuations is so singular that beyond some order the perturbative expansion breaks down. The topological classification of finite-energy, periodic fields is presented and the classical solutions which minimize the action in each topological sector are examined. These include periodic instantons and magnetic monopoles. At sufficiently high temperature only fields with integral topological charge can contribute to the functional integral. Electric screening completely suppresses the contribution of fields with nonintegral topological charge. Consequently the $\ensuremath{\theta}$ dependence of the free energy at high temperature is dominated by the contribution of instantons. The complete temperature dependence of the instanton density is explicitly computed and large-scale instantons are found to be suppressed. Therefore the effects of instantons may be reliably calculated at sufficiently high temperature. The behavior of the theory in the vicinity of the transition from the high-temperature quark phase to the low-temperature hadronic phase cannot be accurately computed. However, at least in the absence of light quarks, semiclassical techniques and lattice methods may be combined to yield a simple picture of the dynamics valid for both high and low temperature, and to estimate the transition temperature.
2,452 citations
CERN1
TL;DR: In this paper, a recently proposed gauge theory for strong interactions, in which the set of planar diagrams play a dominant role, is considered in one space and one time dimension, and it can be reduced to self-energy and ladder diagrams, and they can be summed.
1,872 citations
TL;DR: In this paper, it was shown that the Meissner effect can be maintained in the quasi-particle picture by taking into account a certain class of corrections to the chargecurrent operator due to the phonon and Coulomb interaction.
Abstract: Ideas and techniques known in quantum electrodynamics have been applied to the Bardeen-Cooper-Schrieffer theory of superconductivity In an approximation which corresponds to a generalization of the Hartree-Fock fields, one can write down an integral equation defining the self-energy of an electron in an electron gas with phonon and Coulomb interaction The form of the equation implies the existence of a particular solution which does not follow from perturbation theory, and which leads to the energy gap equation and the quasi-particle picture analogous to Bogoliubov'sThe gauge invariance, to the first order in the external electromagnetic field, can be maintained in the quasi-particle picture by taking into account a certain class of corrections to the chargecurrent operator due to the phonon and Coulomb interaction In fact, generalized forms of the Ward identity are obtained between certain vertex parts and the self-energy The Meissner effect calculation is thus rendered strictly gauge invariant, but essentially keeping the BCS result unaltered for transverse fieldsIt is shown also that the integral equation for vertex parts allows homogeneous solutions which describe collective excitations of quasi-particle pairs, and the nature and effects of such collective states are discussed
1,666 citations
TL;DR: In this paper, a review of the results of the density-functional type of electronic structure calculations is presented, and their results are compared with the relevant experimental data, showing that the important electronic states are dominated by the copper and oxygen orbitals, with strong hybridization between them.
Abstract: Since the discovery of superconductivity above 30 K by Bednorz and M\"uller in the La copper oxide system, the critical temperature has been raised to 90 K in Y${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ and to 110 and 125 K in Bi-based and Tl-based copper oxides, respectively. In the two years since this Nobel-prize-winning discovery, a large number of electronic structure calculations have been carried out as a first step in understanding the electronic properties of these materials. In this paper these calculations (mostly of the density-functional type) are gathered and reviewed, and their results are compared with the relevant experimental data. The picture that emerges is one in which the important electronic states are dominated by the copper $d$ and oxygen $p$ orbitals, with strong hybridization between them. Photon, electron, and positron spectroscopies provide important information about the electronic states, and comparison with electronic structure calculations indicates that, while many features can be interpreted in terms of existing calculations, self-energy corrections ("correlations") are important for a more detailed understanding. The antiferromagnetism that occurs in some regions of the phase diagram poses a particularly challenging problem for any detailed theory. The study of structural stability, lattice dynamics, and electron-phonon coupling in the copper oxides is also discussed. Finally, a brief review is given of the attempts so far to identify interaction constants appropriate for a model Hamiltonian treatment of many-body interactions in these materials.
1,435 citations
TL;DR: The nature of Vxc and the self-energy in real space is discussed, features and trends found in Si, GaAs, AlAs, and diamond are investigated, and the relationship of the calculated Vxc to the LDA and its extensions is examined.
Abstract: We show how the density-functional theory (DFT) exchange-correlation potential ${V}_{\mathrm{xc}(\mathrm{r}}$) of a semiconductor is calculated from the self-energy operator \ensuremath{\Sigma}(r,r',\ensuremath{\omega}), and how \ensuremath{\Sigma} is obtained using the one-particle Green's function and the screened Coulomb interaction (the GW approximation). We discuss the nature of ${V}_{\mathrm{xc}}$ and the self-energy in real space, and investigate features and trends found in Si, GaAs, AlAs, and diamond. In each case the calculated quasiparticle band structure is in good agreement with experiment, while the DFT band structure is surprisingly similar to that with the common local-density approximation (LDA); in particular, about 80% of the severe LDA band-gap error is shown to be inherent in DFT calculations, being accounted for by the discontinuity \ensuremath{\Delta} in ${V}_{\mathrm{xc}}$ upon addition of an electron. The relationship of the calculated ${V}_{\mathrm{xc}}$ to the LDA and its extensions is also examined.
1,371 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2025 | 5 |
| 2024 | 14 |
| 2023 | 13 |
| 2022 | 25 |
| 2021 | 26 |
| 2020 | 26 |