scholarly journals Derivation of static low-energy effective models by anab initiodownfolding method without double counting of Coulomb correlations: Application to SrVO3, FeSe, and FeTe

2013 ◽  
Vol 87 (19) ◽  
Author(s):  
Motoaki Hirayama ◽  
Takashi Miyake ◽  
Masatoshi Imada
Keyword(s):  
Low Energy ◽  
Double Counting ◽  
Effective Models ◽  
Coulomb Correlations

scholarly journals Renormalization group consistency and low-energy effective theories

2019 ◽  
Vol 6 (5) ◽  
Author(s):  
Jens Braun ◽  
Marc Leonhardt ◽  
Jan M. Pawlowski
Keyword(s):  
Renormalization Group ◽  
Mean Field ◽  
Bound State ◽  
Field Approximation ◽  
Low Energy ◽  
Mean Field Approximation ◽  
Quantum Field Theories ◽  
Model Calculations ◽  
Effective Models ◽  
Effective Theories

Low-energy effective theories have been used very successfully to study the low-energy limit of QCD, providing us with results for a plethora of phenomena, ranging from bound-state formation to phase transitions in QCD. These theories are consistent quantum field theories by themselves and can be embedded in QCD, but typically have a physical ultraviolet cutoff that restricts their range of validity. Here, we provide a discussion of the concept of renormalization group consistency, aiming at an analysis of cutoff effects and regularization-scheme dependences in general studies of low-energy effective theories. For illustration, our findings are applied to low-energy effective models of QCD in different approximations including the mean-field approximation. More specifically, we consider hot and dense as well as finite systems and demonstrate that violations of renormalization group consistency affect significantly the predictive power of the corresponding model calculations.

scholarly journals Trace and Axial Anomalies on Equal Footing

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Renata Jora
Keyword(s):  
Important Application ◽  
Low Energy ◽  
Equal Footing ◽  
Generalized Symmetry ◽  
Single Complex ◽  
Effective Models

We discussed that for some particular nonsupersymmetric theories, a generalized symmetry that includes both the scale and axial transformations and leads to a single current may contain also a pseudoscalar term. The method, inspired by the superconformal anomalies, has important application for low-energy effective models where it allows the introduction of a single complex glueball field with a scalar and a pseudoscalar component on the same footing with the complex meson nonet fields made of quarks. Both axial and trace anomalies are satisfied in accordance to the meson structure and the QCD requirements.

πº → γγ DECAY AND THE CONSTITUENT-QUARK VALUE FOR gA

1994 ◽  
Vol 09 (11) ◽  
pp. 955-958 ◽  
Author(s):  
A. S. DEAKIN ◽  
V. ELIAS ◽  
M. D. SCADRON
Keyword(s):  
Decay Rate ◽  
Constituent Quark ◽  
Low Energy ◽  
Effective Models

Consideration of the π° → γγ decay rate in effective models for low energy QCD suggests that the constituent-quark value of gA is quite close to unity.

scholarly journals On anomalies in effective models with nonlinear symmetry realization

2020 ◽  
Vol 35 (35) ◽  
pp. 2050294
Author(s):  
Andrej Arbuzov ◽  
Boris Latosh
Keyword(s):  
Effective Action ◽  
Conformal Symmetry ◽  
Low Energy ◽  
Energy Dynamics ◽  
Effective Models ◽  
Simple Models

Anomalous features of models with nonlinear symmetry realization are addressed. It is shown that such models can have anomalous amplitudes breaking of its original symmetry realization. An illustrative example of a simple models with a nonlinear conformal symmetry realization is given. It is argued that the effective action obtained via nonlinear symmetry realization should be used to obtain an anomaly-induced action which is to drive the low-energy dynamics.

scholarly journals Frustrated Quantum Rare-Earth Pyrochlores

2019 ◽  
Vol 10 (1) ◽  
pp. 357-386 ◽  
Author(s):  
Jeffrey G. Rau ◽  
Michel J.P. Gingras
Keyword(s):  
Rare Earth ◽  
Exchange Interactions ◽  
Low Energy ◽  
Quantum Phases ◽  
Important Material ◽  
Alternative Material ◽  
Effective Models ◽  
Key Questions

In this review, we provide an introduction to the physics of a series of frustrated quantum rare-earth pyrochlores. We first give a background on the microscopic single- and two-ion physics of these materials, discussing the origins and properties of their exchange interactions and their minimal low-energy effective models before outlining what is known about their classical and quantum phases. We then make use of this understanding to discuss four important material examples, Er2Ti2O7, Yb2Ti2O7, Tb2Ti2O7, and Pr2Zr2O7, covering in some detail what is known experimentally and theoretically for each and then summarizing some key questions that remain open. Finally, we offer an outlook on some alternative material platforms for realizing similar physics and discuss what we see as prospects for future investigations on these quantum rare-earth pyrochlores.

Dissociated Σ=27 boundaries in silicon

1988 ◽  
Vol 46 ◽  
pp. 624-625
Author(s):  
A. Garg ◽  
W.A.T. Clark ◽  
J.P. Hirth
Keyword(s):  
Electron Diffraction ◽  
Local Minimum ◽  
Boundary Energy ◽  
Coincidence Site Lattice ◽  
Boundary Plane ◽  
Low Energy ◽  
Theoretical Understanding ◽  
Site Lattice ◽  
Kikuchi Pattern ◽  
Analysis Techniques

In the last twenty years, a significant amount of work has been done in the theoretical understanding of grain boundaries. The various proposed grain boundary models suggest the existence of coincidence site lattice (CSL) boundaries at specific misorientations where a periodic structure representing a local minimum of energy exists between the two crystals. In general, the boundary energy depends not only upon the density of CSL sites but also upon the boundary plane, so that different facets of the same boundary have different energy. Here we describe TEM observations of the dissociation of a Σ=27 boundary in silicon in order to reduce its surface energy and attain a low energy configuration.The boundary was identified as near CSL Σ=27 {255} having a misorientation of (38.7±0.2)°/[011] by standard Kikuchi pattern, electron diffraction and trace analysis techniques. Although the boundary appeared planar, in the TEM it was found to be dissociated in some regions into a Σ=3 {111} and a Σ=9 {122} boundary, as shown in Fig. 1.

Transfer optics for high spatial resolution electron spectroscopy

1988 ◽  
Vol 46 ◽  
pp. 666-667
Author(s):  
G. G. Hembree ◽  
Luo Chuan Hong ◽  
P.A. Bennett ◽  
J.A. Venables
Keyword(s):  
Magnetic Field ◽  
Scanning Transmission Electron Microscope ◽  
Low Energy ◽  
Objective Lens ◽  
State University ◽  
Arizona State University ◽  
Initial Field ◽  
Resolution Electron ◽  
Scanning Transmission ◽  
Low Energy Electrons

A new field emission scanning transmission electron microscope has been constructed for the NSF HREM facility at Arizona State University. The microscope is to be used for studies of surfaces, and incorporates several surface-related features, including provision for analysis of secondary and Auger electrons; these electrons are collected through the objective lens from either side of the sample, using the parallelizing action of the magnetic field. This collimates all the low energy electrons, which spiral in the high magnetic field. Given an initial field Bi∼1T, and a final (parallelizing) field Bf∼0.01T, all electrons emerge into a cone of semi-angle θf≤6°. The main practical problem in the way of using this well collimated beam of low energy (0-2keV) electrons is that it is travelling along the path of the (100keV) probing electron beam. To collect and analyze them, they must be deflected off the beam path with minimal effect on the probe position.

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