Second-order self-energy for the Anderson model analytical results

1979 ◽  
Vol 91 (1) ◽  
pp. 355-360 ◽  
Author(s):  
J. Zieliński ◽  
B. Kozarzewski
Keyword(s):  
Anderson Model ◽  
Second Order ◽  
Self Energy ◽  
Analytical Results

scholarly journals Second-Order Electron Self-Energy in Hydrogenlike Ions

1999 ◽  
Vol 83 (12) ◽  
pp. 2312-2315 ◽  
Author(s):  
Igor Goidenko ◽  
Leonti Labzowsky ◽  
Andrei Nefiodov ◽  
Günter Plunien ◽  
Gerhard Soff
Keyword(s):  
Second Order ◽  
Self Energy

LOCAL MOMENT ORDERING IN PERIODIC ANDERSON MODEL

2001 ◽  
Vol 15 (19n20) ◽  
pp. 2583-2594 ◽  
Author(s):  
A. RAMAKANTH ◽  
W. NOLTING ◽  
G. G. REDDY ◽  
D. MEYER ◽  
S. SCHWIEGER
Keyword(s):  
Magnetic Properties ◽  
Spectral Density ◽  
Anderson Model ◽  
Magnetic Ordering ◽  
High Energy ◽  
Localized States ◽  
Periodic Anderson Model ◽  
Self Energy ◽  
Atomic Limit ◽  
Comparison Of The Results

Strongly correlated electron systems are studied with the help of periodic Anderson model (PAM). The PAM in which highly correlated nondegenerate localized states form a subsystem is considered and the focus of study is on magnetic ordering of electrons in these localized states. In order to study the PAM, which is not amenable to exact solution, two approximate schemes are proposed. The first one is called the spectral density approximation (SDA). Guided by the atomic limit, a two-pole ansatz is made for the localized electron spectral density. The spectral weights and the quasiparticle energies are determined by a moment method. From the spectral density, the spin and energy dependent self-energy is evaluated. A principal limitation of this method is that per ansatz, the quasiparticles are of infinite lifetime. To introduce a finite lifetime, a second approximation scheme is proposed where coherent potential approximation (CPA) is applied to PAM. In order to do CPA, an alloy analogy (AA) is required. In the conventional AA, the concentrations α and the atomic levels E of the fictitious alloy are taken from the atomic limit. Since the interest is in the magnetic properties, this AA is not appropriate. Therefore, a modified AA (MAA) is proposed. In MAA, α and E are obtained using the high energy expansion of the Green's function and the self-energy. In both the approximations, the density of states and the magnetization are selfconsistently evaluated and a phase diagram is obtained. Comparison of the results of the two schemes brings out the effect of quasiparticle damping on the magnetic properties.

scholarly journals Field Line Pitch and Local Magnetic Shear in Tokamaks

1996 ◽  
Vol 49 (6) ◽  
pp. 1121
Author(s):  
JLV Lewandowski ◽  
M Persson
Keyword(s):  
Aspect Ratio ◽  
Field Line ◽  
Second Order ◽  
Tokamak Plasma ◽  
Magnetic Shear ◽  
Analytical Results

The field line pitch and its relation to the integrated magnetic shear is discussed for a low-β tokamak plasma. Analytical results using a second order inverse aspect ratio expansion are presented and specifically discussed in the limits of peaked and fiat current profiles. The results are compared and contrasted with an earlier calculation of the local magnetic shear.

scholarly journals EXACT ${\mathcal O}(g^2\alpha_s)$ TOP DECAY WIDTH FROM GENERAL MASSIVE TWO-LOOP INTEGRALS

2000 ◽  
Vol 15 (14) ◽  
pp. 925-929 ◽  
Author(s):  
ADRIAN GHINCULOV ◽  
YORK-PENG YAO
Keyword(s):  
Decay Width ◽  
Top Quark ◽  
Quark Mass ◽  
Previous Article ◽  
Radiative Corrections ◽  
Self Energy ◽  
Analytical Results ◽  
B Quark ◽  
Mass Expansion ◽  
Text Correction

We calculate the b-dependent self-energy of the top-quark at [Formula: see text] by using a general massive two-loop algorithm proposed in a previous article. From this we derive by unitarity the [Formula: see text] radiative corrections to the decay width of the top quark, where all effects associated with the b-quark mass are included without resorting to a mass expansion. Our results agree with the analytical results available for the [Formula: see text] correction to the top-quark width.

Second-order self-energy–vacuum-polarization contributions to the Lamb shift in highly charged few-electron ions

1996 ◽  
Vol 54 (4) ◽  
pp. 2805-2813 ◽  
Author(s):  
Hans Persson ◽  
Ingvar Lindgren ◽  
Leonti N. Labzowsky ◽  
Günter Plunien ◽  
Thomas Beier ◽  
...  
Keyword(s):  
Lamb Shift ◽  
Vacuum Polarization ◽  
Second Order ◽  
Self Energy

Second order self-energy of the two-dimensional Hubbard model

1997 ◽  
Vol 103 (1) ◽  
pp. 41-44 ◽  
Author(s):  
Stéphane Daul ◽  
Michael Dzierzawa
Keyword(s):  
Hubbard Model ◽  
Second Order ◽  
Two Dimensional ◽  
Self Energy
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