Connection between equation of motion and perturbation theory approach to the evaluation of double time spin Green functions

1970 ◽  
Vol 3 (7) ◽  
pp. 1462-1482 ◽  
Author(s):  
F Leoni ◽  
C R Natoli
Keyword(s):  
Perturbation Theory ◽  
Equation Of Motion ◽  
Green Functions ◽  
Theory Approach ◽  
Double Time

Perturbation theory for double-time temperature-dependent Green functions

1962 ◽  
Vol 11 (44) ◽  
pp. 317-348 ◽  
Author(s):  
S.V. Tyablikov ◽  
V.L. Bonch-Bruevich
Keyword(s):  
Perturbation Theory ◽  
Green Functions ◽  
Temperature Dependent ◽  
Double Time

scholarly journals Perturbation theory approach to predict the covariance matrices of the galaxy power spectrum and bispectrum in redshift space

2020 ◽  
Vol 497 (2) ◽  
pp. 1684-1711 ◽  
Author(s):  
Naonori S Sugiyama ◽  
Shun Saito ◽  
Florian Beutler ◽  
Hee-Jong Seo
Keyword(s):  
Perturbation Theory ◽  
Power Spectrum ◽  
Shot Noise ◽  
Signal To Noise Ratio ◽  
Covariance Matrices ◽  
Theory Approach ◽  
Cross Covariance ◽  
The Galaxy ◽  
The Cross ◽  
Non Gaussian

ABSTRACT In this paper, we predict the covariance matrices of both the power spectrum and the bispectrum, including full non-Gaussian contributions, redshift space distortions, linear bias effects, and shot-noise corrections, using perturbation theory (PT). To quantify the redshift-space distortion effect, we focus mainly on the monopole and quadrupole components of both the power and bispectra. We, for the first time, compute the 5- and 6-point spectra to predict the cross-covariance between the power and bispectra, and the autocovariance of the bispectrum in redshift space. We test the validity of our calculations by comparing them with the covariance matrices measured from the MultiDark-Patchy mock catalogues that are designed to reproduce the galaxy clustering measured from the Baryon Oscillation Spectroscopic Survey Data Release 12. We argue that the simple, leading-order PT works because the shot-noise corrections for the Patchy mocks are more dominant than other higher order terms we ignore. In the meantime, we confirm some discrepancies in the comparison, especially of the cross-covariance. We discuss potential sources of such discrepancies. We also show that our PT model reproduces well the cumulative signal-to-noise ratio of the power spectrum and the bispectrum as a function of maximum wavenumber, implying that our PT model captures successfully essential contributions to the covariance matrices.

Nonequilibrium Density of State of a Kondo Dot Coupled to Luttinger Liquid

2012 ◽  
Vol 622-623 ◽  
pp. 1826-1829
Author(s):  
Kai Hua Yang ◽  
Yang Chen ◽  
Bei Yun Liu ◽  
Xian He
Keyword(s):  
Density Of States ◽  
Bias Voltage ◽  
Strong Interaction ◽  
Luttinger Liquid ◽  
Equation Of Motion ◽  
Green Functions ◽  
Zero Temperature ◽  
Density Of State ◽  
Weakly Coupled ◽  
Kondo Physics

We theoretically investigate the nonequilibrium density of states (DOS) of a Kondo dot weakly coupled to Luttinger liquid leads by using the equation-of-motion technique of non-equilibrium Green functions. The joint effects of large bias voltage and moderately strong intralead interactions results in nontrivial modifications of the Kondo peak in the DOS. The DOS exhibits a two-channel Kondo physics for moderately strong interaction in the leads at zero temperature.

scholarly journals THE BOLTZMANN EQUATION IN SCALAR FIELD THEORY

1998 ◽  
Vol 13 (24) ◽  
pp. 4281-4288 ◽  
Author(s):  
F. T. BRANDT ◽  
J. FRENKEL ◽  
A. GUERRA
Keyword(s):  
Field Theory ◽  
Scalar Field ◽  
Temperature Limit ◽  
Equation Of Motion ◽  
Green Functions ◽  
Static Case ◽  
Quantum Field ◽  
Scalar Field Theory ◽  
High Temperature Limit ◽  
Classical Transport

We derive the classical transport equation, in scalar field theory with a g2V(ϕ) interaction, from the equation of motion for the quantum field. We obtain a very simple, but iterative, expression for the effective action Γ which generates all the n-point Green functions in the high-temperature limit. An explicit and closed form is given for Γ in the static case.

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