scholarly journals Lattice QCD Study for Gluon Propagator and Gluon Spectral Function

2011 ◽  
Author(s):  
Hideo Suganuma ◽  
Takumi Iritani ◽  
Arata Yamamoto ◽  
Hideaki Iida
Keyword(s):  
Lattice Qcd ◽  
Spectral Function ◽  
Gluon Propagator

scholarly journals LATTICE QCD GLUON PROPAGATORS NEAR TRANSITION TEMPERATURE

2012 ◽  
Vol 27 (09) ◽  
pp. 1250050 ◽  
Author(s):  
V. G. BORNYAKOV ◽  
V. K. MITRJUSHKIN
Keyword(s):  
Transition Temperature ◽  
Lattice Qcd ◽  
Finite Volume ◽  
Momentum Space ◽  
Transition Point ◽  
Gluon Propagator ◽  
Landau Gauge ◽  
Volume Dependence ◽  
Gauge Fixing ◽  
Two Phases

Landau gauge gluon propagators are studied numerically in the SU (3) gluodynamics as well as in the full QCD with the number of flavors nF = 2 using efficient gauge fixing technique. We compare these propagators at temperatures very close to the transition point in two phases: confinement and deconfinement. The electric mass mE has been determined from the momentum space longitudinal gluon propagator. Gribov copy effects are found to be rather strong in the gluodynamics, while in the full QCD case they are weak ("Gribov noise"). Also we analyze finite volume dependence of the transverse and longitudinal propagators.

scholarly journals ABELIAN PROJECTION AND STUDIES OF GAUGE-VARIANT QUANTITIES IN THE LATTICE QCD WITHOUT GAUGE FIXING

1996 ◽  
Vol 11 (13) ◽  
pp. 1081-1093 ◽  
Author(s):  
SERGEI V. SHABANOV
Keyword(s):  
Lattice Qcd ◽  
Continuum Limit ◽  
Gluon Propagator ◽  
Lorentz Invariance ◽  
Gauge Condition ◽  
Gauge Fields ◽  
Gauge Invariant ◽  
Dynamical Reduction ◽  
Gauge Fixing ◽  
The Continuum

We suggest a new (dynamical) Abelian projection of the lattice QCD. It contains no gauge condition imposed on gauge fields so that Gribov copying is avoided. Configurations of gauge fields that turn into monopoles in the Abelian projection can be classified in a gauge-invariant way. In the continuum limit, the theory respects the Lorentz invariance. A similar dynamical reduction of the gauge symmetry is proposed for studies of gauge-variant correlators (like a gluon propagator) in the lattice QCD. Though the procedure is harder for numerical simulations, it is free of gauge-fixing artifacts, like the Gribov horizon and copies.

scholarly journals An estimate for the thermal photon rate from lattice QCD

2018 ◽  
Vol 175 ◽  
pp. 07044 ◽  
Author(s):  
Bastian B. Brandt ◽  
Anthony Francis ◽  
Tim Harris ◽  
Harvey B. Meyer ◽  
Aman Steinberg
Keyword(s):  
Lattice Qcd ◽  
Spectral Function ◽  
Production Rate ◽  
Vector Current ◽  
Gluon Plasma ◽  
Vector Channel ◽  
New Correlation ◽  
Current Correlation ◽  
Direct Model ◽  
Ill Posed

We estimate the production rate of photons by the quark-gluon plasma in lattice QCD. We propose a new correlation function which provides better control over the systematic uncertainty in estimating the photon production rate at photon momenta in the range πT/2 to 2πT. The relevant Euclidean vector current correlation functions are computed with Nf = 2 Wilson clover fermions in the chirally-symmetric phase. In order to estimate the photon rate, an ill-posed problem for the vector-channel spectral function must be regularized. We use both a direct model for the spectral function and a modelindependent estimate from the Backus-Gilbert method to give an estimate for the photon rate.

scholarly journals A STUDY OF GLUON PROPAGATOR ON COARSE LATTICE

2000 ◽  
Vol 15 (04) ◽  
pp. 229-244 ◽  
Author(s):  
J. P. MA
Keyword(s):  
Lattice Qcd ◽  
Smooth Function ◽  
Qualitative Agreement ◽  
Lattice Spacing ◽  
Continuum Limit ◽  
Gluon Propagator ◽  
Landau Gauge ◽  
Lattice Action ◽  
Lattice Volume ◽  
The Continuum

We study gluon propagator in Landau gauge with lattice QCD, where we use an improved lattice action. The calculation of gluon propagator is performed on lattices with the lattice spacing from 0.40 fm to 0.24 fm and with the lattice volume from (2.40 fm )4 to (4.0 fm )4. We find that the rotation invariance is approximately restored in the q2-range, indicated by the fact that the propagator is a smooth function of the continuum momentum q2. We try to fit our results by two different ways, in the first one we interpret the calculated gluon propagators as a function of the continuum momentum, while in the second we interpret the propagators as a function of the lattice momentum. In both cases we use models which are the same in continuum limit. A qualitative agreement between two fittings is found.

scholarly journals Two-point functions of quenched lattice QCD in Numerical Stochastic Perturbation Theory. (II) The gluon propagator in Landau gauge

2011 ◽  
Vol 842 (1) ◽  
pp. 122-139 ◽  
Author(s):  
F. Di Renzo ◽  
E.-M. Ilgenfritz ◽  
H. Perlt ◽  
A. Schiller ◽  
C. Torrero
Keyword(s):  
Perturbation Theory ◽  
Lattice Qcd ◽  
Gluon Propagator ◽  
Stochastic Perturbation ◽  
Landau Gauge

scholarly journals POSITIVITY VIOLATIONS IN QCD

2013 ◽  
Vol 28 (38) ◽  
pp. 1330035 ◽  
Author(s):  
JOHN M. CORNWALL
Keyword(s):  
Spectral Function ◽  
Physical Interpretation ◽  
Gluon Propagator ◽  
Landau Gauge ◽  
Asymptotic Freedom ◽  
Theoretical Studies ◽  
Gauge Invariant ◽  
Superconvergence Relation

Both lattice simulations and theoretical studies show that the spectral function of the gluon propagator of QCD (in various gauges, as well as for the gauge-invariant Pinch Technique, or PT, propagator) is not nonnegative everywhere, although it should be if it has a physical interpretation as in QED. Theory says moreover that the non-positive spectral function of the Landau-gauge or of the PT gluon propagator is further constrained to obey a superconvergence relation (the integral of the spectral function vanishes). We review the theoretical and lattice evidence for violation of positivity as well as various interpretations of this violation, and consider methods for checking superconvergence on the lattice (so far undone). The most common interpretation is that positivity violation implies confinement of gluons, so the gluon propagator does not describe processes with physical gluons. Another more direct and gauge-invariant interpretation arises from the PT: Asymptotic freedom alone demands non-positivity and superconvergence.

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