Correlation of the ghost and the quark in the lattice landau gauge QCD

Nakajima

2007

Phys. Rev. D

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The color diagonal and color antisymmetric ghost propagators slightly above Tc of N f = 2 MILC 24 3 × 12 lattices are measured and compared with zero temperature unquenched N f = 2 + 1 MILCc 20 3 × 64 and MILC f 28 3 × 96 lattices and zero temperature quenched 56 4 β = 6.4 and 6.45 lattices. The expectation value of the color antisymmetric ghost propagator φ c (q) is zero but its Binder cumulant, which is consistent with that of N 2 c − 1 dimensional Gaussian distribution below Tc, decreases above Tc. Although the color diagonal ghost propagator is temperature independent, the l 1 norm of the color antisymmetric ghost propagator is temperature dependent. The expectation value of the ghost condensate observed at zero temperature unquenched configuration is consistent with 0 in T > Tc.We also measure transverse, magnetic and electric gluon propagator and extract gluon screening masses. The running coupling measured from the product of the gluon dressing function and the ghost dressing function are almost temperature independent but the effect of A 2 condensate observed at zero temperature is consistent with 0 in T > Tc.The transverse gluon dressing function at low temperature has a peak in the infrared at low temperature but it becomes flatter at high temperature. The magnetic gluon propagator at high momentum depends on the temperature. These data imply that the magnetic gluon propagator and the color antisymmetric ghost propagator are affected by the presence of dynamical quarks and there are strong non-perturbative effects through the temperature-dependent color anti-symmetric ghost propagator.

Section: Introductionsupporting

confidence: 64%

Section: The Color Antisymmetric Ghost Propagatormentioning

confidence: 93%

Section: The Color Antisymmetric Ghost Propagatormentioning

confidence: 99%

Section: B Milc Zero Temperature 28mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Infrared features of unquenched finite temperature lattice Landau gauge QCD

Nakajima

2007

Phys. Rev. D

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Roles of the Color Antisymmetric Ghost Propagator in the Infrared QCD

2008

Few-Body Syst

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The results of Coulomb gauge and Landau gauge lattice QCD simulation do not agree completely with continuum theory. There are indications that the ghost propagator in the infrared region has strong fluctuation whose modulus is compatible with that of the color diagonal ghost propagator. After presenting lattice simulation of configurations produced with Kogut-Susskind fermion (MILC collaboration) and those with domain wall fermion (RBC/UKQCD collaboration), I investigate in triple gluon vertex and the ghost-gluon-ghost vertex how the square of the color antisymmetric ghost contributes. Then the effect of the vertex correction to the gluon propagator and the ghost propagator is investigated.Recent Dyson-Schwinger equation analysis suggests the ghost dressing function G(0) = finite and no infrared enhancement or α G = 0. But the ghost propagator renormalized by the loop containing a product of color antisymmetric ghost is expected to behave as < cc > r = − G(q 2 ) q 2 with G(q 2 ) ∝ q −2α G with α G = 0.5, if the fixed point scenario is valid. I interpret the α G = 0 solution should contain a vertex correction. The infrared exponent of our lattice Landau gauge gluon propagator of the RBC/UKQCD is α D = −0.5 and that of MILC is about -0.7.A possible interpretation of the origin of the fluctuation is given. *

Propagator of the Lattice Domain Wall Fermion and the Staggered Fermion

2009

Few-Body Syst

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We calculate the propagator of the domain wall fermion (DWF) of the RBC/UKQCD collaboration with 2+1 dynamical flavors of 16 3 × 32 × 16 lattice in Coulomb gauge, by applying the conjugate gradient method. We find that the fluctuation of the propagator is small when the momenta are taken along the diagonal of the 4-dimensional lattice. Restricting momenta in this momentum region, which is called the cylinder cut, we compare the mass function and the running coupling of the quark-gluon coupling α s,g 1 (q) with those of the staggerd fermion of the MILC collaboration in Landau gauge.In the case of DWF, the ambiguity of the phase of the wave function is adjusted such that the overlap of the solution of the conjugate gradient method and the plane wave at the source becomes real. The quark-gluon coupling α s,g 1 (q) of the DWF in the region q > 1.3GeV agrees with ghostgluon coupling α s (q) that we measured by using the configuration of the MILC collaboration, i.e. enhancement by a factor (1 + c/q 2 ) with c ≃ 2.8GeV 2 on the pQCD result.In the case of staggered fermion, in contrast to the ghost-gluon coupling α s (q) in Landau gauge which showed infrared suppression, the quark-gluon coupling α s,g 1 (q) in the infrared region increases monotonically as q → 0. Above 2GeV, the quark-gluon coupling α s,g 1 (q) of staggered fermion calculated by naive crossing becomes smaller than that of DWF, probably due to the complex phase of the propagator which is not connected with the low energy physics of the fermion taste