Single-Particle States in Many-Body Systems

1971 ◽  
pp. 500-511 ◽  
Author(s):  
Seb Doniach
Keyword(s):  
Single Particle ◽  
Many Body ◽  
Many Body Systems

scholarly journals Feynman diagrams and rooted maps

Open Physics ◽  
2018 ◽  
Vol 16 (1) ◽  
pp. 149-167 ◽  
Author(s):  
Andrea Prunotto ◽  
Wanda Maria Alberico ◽  
Piotr Czerski
Keyword(s):  
Single Particle ◽  
Feynman Diagram ◽  
Feynman Diagrams ◽  
Topological Properties ◽  
Many Body ◽  
Perturbative Order ◽  
Original Definition ◽  
Many Body Systems ◽  
Definition Of ◽  
Particle Propagator

Abstract The rooted maps theory, a branch of the theory of homology, is shown to be a powerful tool for investigating the topological properties of Feynman diagrams, related to the single particle propagator in the quantum many-body systems. The numerical correspondence between the number of this class of Feynman diagrams as a function of perturbative order and the number of rooted maps as a function of the number of edges is studied. A graphical procedure to associate Feynman diagrams and rooted maps is then stated. Finally, starting from rooted maps principles, an original definition of the genus of a Feynman diagram, which totally differs from the usual one, is given.

A SOLVABLE MODEL OF INTERACTING MANY BODY SYSTEMS EXHIBITING A BREAKDOWN OF THE BOLTZMANN EQUATION

2014 ◽  
Vol 28 (03) ◽  
pp. 1450046
Author(s):  
B. H. J. McKELLAR
Keyword(s):  
Boltzmann Equation ◽  
Time Dependence ◽  
Single Particle ◽  
Density Operator ◽  
Particle Density ◽  
Solvable Model ◽  
Many Body ◽  
Single Particle Density ◽  
The Boltzmann Equation ◽  
Many Body Systems

In a particular exactly solvable model of an interacting system, the Boltzmann equation predicts a constant single particle density operator, whereas the exact solution gives a single particle density operator with a nontrivial time dependence. All of the time dependence of the single particle density operator is generated by the correlations.

Single-Particle Self-Energy in Many-Body Systems at Finite Temperature

2000 ◽  
Vol 283 (2) ◽  
pp. 308-333 ◽  
Author(s):  
N. Giovanardi ◽  
P. Donati ◽  
P.F. Bortignon ◽  
R.A. Broglia
Keyword(s):  
Single Particle ◽  
Finite Temperature ◽  
Many Body ◽  
Self Energy ◽  
Many Body Systems

THE SURPRISING PHENOMENON OF LEVEL MERGING IN FINITE FERMI SYSTEMS

2008 ◽  
Vol 22 (25n26) ◽  
pp. 4452-4463
Author(s):  
JOHN W. CLARK ◽  
VICTOR A. KHODEL ◽  
HAOCHEN LI ◽  
MIKHAIL V. ZVEREV
Keyword(s):  
Single Particle ◽  
Energy Levels ◽  
Fermi System ◽  
Particle Energy ◽  
Particle Spectrum ◽  
Many Body ◽  
Occupation Numbers ◽  
Inherent Feature ◽  
Wide Range ◽  
Many Body Systems

When applied to a finite Fermi system having a degenerate single-particle spectrum, the Landau-Migdal Fermi-liquid approach leaves room for the possibility that different single-particle energy levels merge with one another. It will be argued that the opportunity for this behavior exists over a wide range of strongly interacting quantum many-body systems. An inherent feature of the mergence phenomenon is the presence of nonintegral quasiparticle occupation numbers, which implies a radical modification of the standard quasiparticle picture. Consequences of this alteration are surveyed for nuclear, atomic, and solid-state systems.

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