scholarly journals Gluon bremsstrahlung by heavy quarks: Its effects on transport coefficients and equilibrium distribution

2014 ◽  
Vol 89 (1) ◽  
Author(s):  
Surasree Mazumder ◽  
Trambak Bhattacharyya ◽  
Jan-e Alam
Keyword(s):  
Equilibrium Distribution ◽  
Transport Coefficients ◽  
Heavy Quarks ◽  
Gluon Bremsstrahlung

scholarly journals Inverse Chapman–Enskog Derivation of the Thermohydrodynamic Lattice-BGK Model for the Ideal Gas

1998 ◽  
Vol 09 (08) ◽  
pp. 1231-1245 ◽  
Author(s):  
B. M. Boghosian ◽  
P. V. Coveney
Keyword(s):  
Thermal Conductivity ◽  
Distribution Function ◽  
Relaxation Time ◽  
Equilibrium Distribution ◽  
Transport Coefficients ◽  
Ideal Gas ◽  
Equilibrium Distribution Function ◽  
Bgk Model ◽  
Constant Relaxation Time ◽  
The Ideal

A thermohydrodynamic lattice-BGK model for the ideal gas was derived by Alexander et al. in 1993, and generalized by McNamara et al. in the same year. In these works, particular forms for the equilibrium distribution function and the transport coefficients were posited and shown to work, thereby establishing the sufficiency of the model. In this paper, we rederive the model from a minimal set of assumptions, and thereby show that the forms assumed for the shear and bulk viscosities are also necessary, but that the form assumed for the thermal conductivity is not. We derive the most general form allowable for the thermal conductivity, and the concomitant generalization of the equilibrium distribution. In this way, we show that it is possible to achieve variable (albeit density-dependent) Prandtl number even within a single-relaxation-time lattice-BGK model. We accomplish this by demanding analyticity of the third moments and traces of the fourth moments of the equilibrium distribution function. The method of derivation demonstrates that certain undesirable features of the model — such as the unphysical dependence of the viscosity coefficients on temperature — cannot be corrected within the scope of lattice-BGK models with constant relaxation time.

scholarly journals Nonperturbative effects on radiative energy loss of heavy quarks

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Shuai Y.F. Liu ◽  
Ralf Rapp
Keyword(s):  
Energy Loss ◽  
Scattering Amplitude ◽  
Transport Coefficients ◽  
Power Spectra ◽  
Heavy Quarks ◽  
Radiative Energy ◽  
Spectral Functions ◽  
Fixed Temperature ◽  
Strong Suppression ◽  
Radiative Energy Loss

Abstract The radiative energy loss of fast partons traveling through the quark-gluon plasma (QGP) is commonly studied within perturbative QCD (pQCD). Nonperturbative (NP) effects, which are expected to become important near the critical temperature, have been much less investigated. Here, we utilize a recently developed T -matrix approach to incorporate NP effects for gluon emission off heavy quarks propagating through the QGP. We set up four cases that contain, starting from a Born diagram calculation with color- Coulomb interaction, an increasing level of NP components, by subsequently including (remnants of ) confining interactions, resummation in the heavy-light scattering amplitude, and off-shell spectral functions for both heavy and light partons. For each case we compute the power spectra of the emitted gluons, heavy-quark transport coefficients (drag and transverse-momentum broadening, $$ \hat{q} $$ q ̂ ), and the path-length dependent energy loss within a “QGP brick” at fixed temperature. Investigating the differences in these quantities between the four cases illustrates how NP mechanisms affect gluon radiation processes. While the baseline perturbative processes experience a strong suppression of soft radiation due to thermal masses of the emitted gluons, confining interactions, ladder resummations and broad spectral functions (re-)generate a large enhancement toward low momenta and low temperatures. For example, for a 10 GeV charm quark at 200 MeV temperature, they enhance the transport coefficients by up to a factor of 10, while the results smoothly converge to perturbative results at sufficiently hard scales.

scholarly journals Drag force on heavy quarks and spatial string tension

2018 ◽  
Vol 33 (06) ◽  
pp. 1850041 ◽  
Author(s):  
Oleg Andreev
Keyword(s):  
String Duality ◽  
Drag Coefficient ◽  
Heavy Quark ◽  
Quark Gluon Plasma ◽  
Diffusion Coefficients ◽  
Transport Coefficients ◽  
Gluon Plasma ◽  
String Tension ◽  
Heavy Quarks ◽  
Strongly Coupled

Heavy quark transport coefficients in a strongly coupled Quark–Gluon Plasma can be evaluated using a gauge/string duality and lattice QCD. Via this duality, one can argue that for low momenta the drag coefficient for heavy quarks is proportional to the spatial string tension. Such a tension is well-studied on the lattice that allows one to straightforwardly make non-perturbative estimates of the heavy quark diffusion coefficients near the critical point. The obtained results are consistent with those in the literature.

Hard gluon bremsstrahlung off heavy quarks in e+e− annihilation

1980 ◽  
Vol 89 (2) ◽  
pp. 225-228 ◽  
Author(s):  
E. Laermann ◽  
P.M. Zerwas
Keyword(s):  
Heavy Quarks ◽  
Hard Gluon ◽  
Gluon Bremsstrahlung

Nonlinear Hydrodynamics of Lattice-Gas Automata with Semi-Detailed Balance

1997 ◽  
Vol 08 (04) ◽  
pp. 653-674
Author(s):  
Alberto Suárez ◽  
Jean Pierre Boon
Keyword(s):  
Lattice Boltzmann ◽  
Lattice Gas ◽  
Equilibrium Distribution ◽  
Local Equilibrium ◽  
Transport Coefficients ◽  
Detailed Balance ◽  
Hydrodynamic Equations ◽  
Nonlinear Hydrodynamics ◽  
Far From Equilibrium ◽  
Dynamical Description

Equations governing the evolution of the hydrodynamic variables in a lattice-gas automaton, arbitrarily far from equilibrium, are derived from the micro-dynamical description of the automaton, under the condition that the local collision rules satisfy semi-detailed balance. This condition guarantees that a factorized local equilibrium distribution (for each node) of the Fermi–Dirac form is invariant under the collision step but not under propagation. The main result is the set of fully nonlinear hydrodynamic equations for the automaton in the lattice-Boltzmann approximation; these equations have a validity domain extending beyond the region close to equilibrium. Linearization of the hydrodynamic equations derived here leads to Green–Kubo formulae for the transport coefficients.

scholarly journals Equilibrium Distribution of Heavy Quarks in Fokker-Planck Dynamics

2000 ◽  
Vol 84 (1) ◽  
pp. 31-34 ◽  
Author(s):  
D. Brian Walton ◽  
Johann Rafelski
Keyword(s):  
Equilibrium Distribution ◽  
Heavy Quarks ◽  
Fokker Planck

scholarly journals Transport coefficients of heavy quarks aroundTcat finite quark chemical potential

2014 ◽  
Vol 90 (5) ◽  
Author(s):  
H. Berrehrah ◽  
P. B. Gossiaux ◽  
J. Aichelin ◽  
W. Cassing ◽  
J. M. Torres-Rincon ◽  
...  
Keyword(s):  
Chemical Potential ◽  
Transport Coefficients ◽  
Heavy Quarks

Baryons with two heavy quarks

2002 ◽  
Vol 172 (5) ◽  
pp. 497 ◽  
Author(s):  
Valerii V. Kiselev ◽  
Anatolii K. Likhoded
Keyword(s):  
Heavy Quarks
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