16612701
IR suppression of the Coulomb gauge gluon propagator in SU(3) Yang-Mills theory
We calculate the equal-time transverse gluon propagator in Coulomb gauge QCD using a SU(3) quenched lattice gauge simulation on large lattices, up to 11 [fm$^4$]. We find that the equal-time gluon propagator shows scaling violation; namely, the data for different lattice spacings do not fall on top of one curve. This problem is cured by discarding data at large momenta, which suffer from discretization errors. In the infrared region, the transverse gluon propagator is strongly suppressed and shows a turnover at about 500 [MeV]. Fitting the power law ansatz to the data at small momenta predicts the vanishing gluon propagator at zero momentum, indicating the confinement of gluons.
118146301
Heavy quark potential at finite imaginary chemical Potential
We investigate chemical-potential (μ) dependence of static-quark free energies in both the real and imaginary μ regions, using the clover-improved two-flavor Wilson fermion action and the renormalization-group improved Iwasaki gauge action. Static-quark potentials are evaluated from the Polyakov-loop correlator in the deconfinement phase and the imaginary μ = iμI region and extrapolated to the real μ region with analytic continuation. As the analytic continuation, the potential calculated at imaginary μ = iμI is expanded into a Taylor-expansion series of iμI/T up to 4th order and the pure imaginary variable iμI/T is replaced by the real one μR/T . At real μ , the 4th-order term weakens μ dependence of the potential sizably. Also, the color-Debye screening mass is extracted from the color-singlet potential at imaginary μ , and the mass is extrapolated to real μ by analytic continuation. The screening mass thus obtained has stronger μ dependence than the prediction of the leading-order thermal perturbation theory at both real and imaginary μ . This talk is based on [1].
17570795
Phase fluctuation of fermion determinant in lattice QCD at finite density
Abstract Once the quark chemical potential μ is introduced in finite density QCD, the fermion determinant appeared in the path integral measure becomes complex. In order to investigate the phase effect of SU (3) lattice QCD (2-flavors), we calculated the fluctuation of the phase of det Δ(μ) on a 8 3 × 4 lattice at μ = 0.1 and 0.2. Then we calculated the chiral condensate and Polyakov line in the no phase and reweighted cases. There is little difference between these two cases at μ = 0.1 and 0.2. We consider a possible reason for this result below μ ≤ 0.27 in terms of Z 3 symmetry.
119503968
Anisotropic improved actions
The studies of the quantum corrections for the anisotropy parameter, η(= ξR/ξB), for the improved actions, β(C0L(Plaq.) + C1L(Rect.)), are proceeded in the medium to strong coupling region on anisotropic lattices. The global features for the η parameters as a function of β and the coefficient C1 have been clarified. It has been found by the perturbative analysis that as C1 decreases, the slope of the η(β) becomes less steep and for the actions whose C1 is less than −0.160, η decreases as β decreases, contrary to the case of the standard action. In the medium to strong coupling region, the η parameter begins to increase as β decreases for all C1. This means that for the actions with C1 < −0.160, the one-loop perturbative results for η break down qualitatively and the η parameters have a dip. As a result of this dip structure the η for Iwasaki's action remains close to unity in the wide range of β, which means that quantum corrections for the anisotropy parameters are small for it.
43999878
Scalar mesons in lattice QCD
Recently there has been renewed and growing interestin scalarmesons[1, 2]. Oneofthe mostnoteworthydevel-opments in this ﬁeld is the re-identiﬁcation of the σ(600)after some twenty years. The results of re-analyses of theπ-π scattering phase shift of the scattering (S) matrixstrongly suggest the existence of the pole of the σ mesonwith I = 0 and J
118532418
EoS of finite density QCD with Wilson fermions by multi-parameter reweighting and Taylor expansion
A bstractThe equation of state (EoS), quark number density and susceptibility at nonzero quark chemical potential μ are studied in lattice QCD simulations with a clover improved Wilson fermion of 2-flavors and RG-improved gauge action. To access nonzero μ, we employ two methods: a multi-parameter reweighting (MPR) in μ and β and Taylor expansion in μ/T. The use of a reduction formula for the Wilson fermion determinant enables to study the reweighting factor in MPR explicitly and higher-order coefficients in Taylor expansion free from errors of noise method, although calculations are limited to small lattice size. As a consequence, we can study the reliability of the thermodynamical quantities through the consistency of the two methods, each of which has different origin of the application limit. The thermodynamical quantities are obtained from simulations on a 83 × 4 lattice with an intermediate quark mass(mPS/mV = 0.8). The MPR and Taylor expansion are consistent for the EoS and number density up to μ/T ~ 0.8 and for the number susceptibility up to μ/T ~ 0.6. This implies within a given statistics that the overlap problem for the MPR and truncation error for the Taylor expansion method are negligible in these regions. In order to make MPR methods work, the fluctuation of the reweighting factor should be small. We derive the equation of the reweighting line where the fluctuation is small, and show that the equation of the reweighting line is consistent with the fluctuation minimum condition.
123256260
Is the Stochastic Gauge-Fixing a Consistent Method for Reducible Gauge Theories?
By using the Stochastic Gauge-Fixing term derived in a previous paper, we stochastically quantize the Non-Abelian Antisymmetric Tensor Field theory as an example of the Reducible Gauge Theories. Though all the quantities are finitely computed and the induced vertex really reproduces the full ghost contributions, the uninterpretable terms still remain