scholarly journals Second order transport coefficient from the chiral anomaly at weak coupling: Diagrammatic resummation

2015 ◽  
Vol 92 (1) ◽  
Author(s):  
Amadeo Jimenez-Alba ◽  
Ho-Ung Yee
Keyword(s):  
Transport Coefficient ◽  
Weak Coupling ◽  
Second Order ◽  
Chiral Anomaly

scholarly journals On bulk viscosity at weak and strong ’t Hooft couplings

2020 ◽  
Vol 35 (27) ◽  
pp. 2030012
Author(s):  
Alina Czajka ◽  
Keshav Dasgupta ◽  
Charles Gale ◽  
Sangyong Jeon ◽  
Aalok Misra ◽  
...  
Keyword(s):  
Boltzmann Equation ◽  
Kinetic Theory ◽  
Strong Coupling ◽  
Bulk Viscosity ◽  
Transport Coefficient ◽  
Weak Coupling ◽  
Coupling Analysis ◽  
Underlying Theory ◽  
Hydrodynamical Limit ◽  
Low Energies

Bulk viscosity is an important transport coefficient that exists in the hydrodynamical limit only when the underlying theory is non-conformal. One example being thermal QCD with large number of colors. We study bulk viscosity in such a theory at low energies and at weak and strong ’t Hooft couplings when the temperature is above the deconfinement temperature. The weak coupling analysis is based on Boltzmann equation from kinetic theory whereas the strong coupling analysis uses non-conformal holographic techniques from string and M-theories. Using these, many properties associated with bulk viscosity may be explicitly derived.

scholarly journals Mass-suppressed effects in heavy quark diffusion

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
A. Bouttefeux ◽  
M. Laine
Keyword(s):  
Heavy Quark ◽  
Transport Coefficient ◽  
Quark Mass ◽  
Weak Coupling ◽  
Charm Quark ◽  
Leading Order ◽  
Heavy Quark Mass ◽  
Leading Term ◽  
Working Out

Abstract Many lattice studies of heavy quark diffusion originate from a colour-electric correlator, obtained as a leading term after an expansion in the inverse of the heavy-quark mass. In view of the fact that the charm quark is not particularly heavy, we consider subleading terms in the expansion. Working out correlators up to $$ \mathcal{O} $$ O (1/M2), we argue that the leading corrections are suppressed by $$ \mathcal{O} $$ O (T/M), and one of them can be extracted from a colour-magnetic correlator. The corresponding transport coefficient is non-perturbative already at leading order in the weak-coupling expansion, and therefore requires a non­perturbative determination.

Nonreciprocal two-photon transmission and statistics in the chiral waveguide QED system

2021 ◽  
Author(s):  
Lei Wang ◽  
Zhen Yi ◽  
Li-hui Sun ◽  
Wen-Ju Gu
Keyword(s):  
Weak Coupling ◽  
Single Photon ◽  
Plane Waves ◽  
Bound State ◽  
Second Order ◽  
Strong Coupling Regime ◽  
Destructive Interference ◽  
Intermediate Coupling ◽  
Coupling Region ◽  
Two Photon

Abstract We study the nonreciprocal properties of transmitted photons in the chiral waveguide QED system, including single- and two-photon transmissions and second-order correlations. For the single-photon transmission, the nonreciprocity is induced by the effects of chiral coupling and atomic dissipation in the weak coupling region. It vanishes in the strong coupling regime when the effect of atomic dissipation becomes ignorable. In the case of two-photon transmission, there exist two ways of going through the emitter: independently as plane waves and formation of bound state. Besides the nonreciprocal behavior of plane waves, the bound state that differs in two directions also alters transmission probabilities. In addition, the second-order correlation of transmitted photons depends on the interference between plane wave and bound state. The destructive interference leads to the strong antibunching in the weak coupling region, while the effective formation of bound state leads to the strong bunching in the intermediate coupling region. However, the negligible interactions for left-propagating photons hardly change the statistics of the input coherent state.

Disappearance Voltage Determinations Using a Convergent Beam

1971 ◽  
Vol 29 ◽  
pp. 184-185
Author(s):  
W. L. Bell
Keyword(s):  
Second Order ◽  
Objective Method ◽  
Uniform Thickness ◽  
Rocking Curve ◽  
Crystal Perfection ◽  
Kikuchi Line ◽  
Central Maximum ◽  
Diffraction Patterns ◽  
Convergent Beam ◽  
Beam Technique

Disappearance voltages for second order reflections can be determined experimentally in a variety of ways. The more subjective methods, such as Kikuchi line disappearance and bend contour imaging, involve comparing a series of diffraction patterns or micrographs taken at intervals throughout the disappearance range and selecting that voltage which gives the strongest disappearance effect. The estimated accuracies of these methods are both to within 10 kV, or about 2-4%, of the true disappearance voltage, which is quite sufficient for using these voltages in further calculations. However, it is the necessity of determining this information by comparisons of exposed plates rather than while operating the microscope that detracts from the immediate usefulness of these methods if there is reason to perform experiments at an unknown disappearance voltage.The convergent beam technique for determining the disappearance voltage has been found to be a highly objective method when it is applicable, i.e. when reasonable crystal perfection exists and an area of uniform thickness can be found. The criterion for determining this voltage is that the central maximum disappear from the rocking curve for the second order spot.

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