Spin Fluctuations in Heisenberg Paramagnets. I. Diagrammatic Expansion for the Moments of the Spectral Density at Finite Temperature,

1972 ◽  
Vol 6 (11) ◽  
pp. 4360-4360
Author(s):  
G. F. Reiter
Keyword(s):  
Spectral Density ◽  
Finite Temperature ◽  
Spin Fluctuations

scholarly journals Superconducting coherence length of hole-doped cuprates obtained from electron–boson spectral density function

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jungseek Hwang
Keyword(s):  
Spectral Density ◽  
Coherence Length ◽  
Cooper Pair ◽  
Average Frequency ◽  
Spin Fluctuations ◽  
Fermi Velocity ◽  
Cooper Pairs ◽  
Spectroscopic Techniques ◽  
Microscopic Mechanism ◽  
Superconducting Coherence Length

AbstractElectron–boson spectral density functions (EBSDFs) can be obtained from measured spectra using various spectroscopic techniques, including optical spectroscopy. EBSDFs, known as glue functions, are suggested to have a magnetic origin. Here, we investigated EBSDFs obtained from the measured optical spectra of hole-doped cuprates with wide doping levels, from underdoped to overdoped cuprates. The average frequency of an EBSDF provides the timescale for the spin fluctuations to form Cooper pairs. This timescale is directly associated with retarded interactions between electrons. Using this timescale and Fermi velocity, a reasonable superconducting coherence length, which reflects the size of the Cooper pair, can be extracted. The obtained coherence lengths were consistent with those measured via other experimental techniques. Therefore, the formation of Cooper pairs in cuprates can be explained by spin fluctuations, the timescales of which appear in EBSDFs. Consequently, EBSDFs provide crucial information on the timescale of the microscopic mechanism of Cooper pair formation.

scholarly journals Spectral density analysis of the chiral transition in nf=4 finite temperature QCD

1992 ◽  
Vol 280 (3-4) ◽  
pp. 261-266
Author(s):  
Nelson A. Alves ◽  
Bernd A. Berg ◽  
Dennis W. Duke ◽  
Anders Irbäck ◽  
Sergiu Sanielevici
Keyword(s):  
Spectral Density ◽  
Finite Temperature ◽  
Chiral Transition ◽  
Density Analysis ◽  
Finite Temperature Qcd

scholarly journals Superconducting Coherence Length of Hole-doped Cuprates Obtained From Electron-boson Spectral Density Function

2021 ◽  
Author(s):  
Jungseek Hwang
Keyword(s):  
Spectral Density ◽  
Coherence Length ◽  
Cooper Pair ◽  
Average Frequency ◽  
Spin Fluctuations ◽  
Fermi Velocity ◽  
Cooper Pairs ◽  
Spectroscopic Techniques ◽  
Microscopic Mechanism ◽  
Superconducting Coherence Length

Abstract Electron{boson spectral density functions (EBSDFs) can be obtained from measured spectra using various spectroscopic techniques, including optical spectroscopy. EBSDFs, known as glue functions, have a magnetic origin. Here, we investigated EBSDFs obtained from the measured optical spectra of hole-doped cuprates with wide doping levels, from underdoped to overdoped cuprates. The average frequency of an EBSDF provides the timescale for the spin fluctuations to form Cooper pairs. This timescale is directly associated with retarded interactions betweenelectrons. Using this timescale and Fermi velocity, a reasonable superconducting coherence length, which reflects the size of the Cooper pair, can be extracted. The obtained coherence lengths were consistent with those measured via other experimental techniques. Therefore, the formation of Cooper pairs in cuprates can be explained by spin fluctuations, the timescales of which appear in EBSDFs. Consequently, EBSDFs provide crucial information on the timescale of the microscopic mechanism of Cooper pair formation.

scholarly journals Finite temperature gluon propagator in Landau gauge: non-zero Matsubara frequencies and spectral densities

2018 ◽  
Vol 175 ◽  
pp. 07038 ◽  
Author(s):  
Paulo J. Silva ◽  
Orlando Oliveira ◽  
David Dudal ◽  
Martin Roelfs
Keyword(s):  
Spectral Density ◽  
Finite Temperature ◽  
Gluon Propagator ◽  
Landau Gauge ◽  
Discrepancy Principle ◽  
Spectral Densities ◽  
Tikhonov Regularisation ◽  
Morozov Discrepancy Principle ◽  
Lattice Computation

We report on the lattice computation of the Landau gauge gluon propagator at finite temperature, including the non-zero Matsubara frequencies. Moreover, the corresponding Källén-Lehmann spectral density is computed, using a Tikhonov regularisation together with the Morozov discrepancy principle. Implications for gluon confinement are also discussed.

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