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.
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].
121904969
Elastic Pion-Deuteron Scattering and Dibaryon Resonances
We show that effects of dibaryon resonances can be clearly seen in the data on the differential cross section of red elastic scattering. Giving the formulation of the Glauber model with the resonance formation term in red direct channel in detail and analyzing all the data presently available by this model, we find that at least two resonances are needed in red direct channel in order to explain the data. One of them may be 'F, (2. 25 GeV) state of two nucleons which was found at Argonne and the other has mass value around ~.5GeV. The data are not enough to determine the spin-parity of the latter but ()' seems somewhat preferable. The branching ratios of the resonances into red system are also given.
22209692
Color confinement and the Faddeev-Popov ghosts in Coulomb gauge QCD
We investigate the Gribov-Zwanziger scenario in the Coulomb gauge using a SU(3) quenched lattice gauge simulation. The dressing function of the ghost propagator diverges in the infrared limit. This result is expected from the fact that the Faddeev-Popov eigenvalue density gets concentrated near the vanishing eigenvalue compared to that in the abelian gauge theory. The turnover of the transversal gluon propagator is not observed up to the largest lattice volume explored in this study. The instantaneous part of the time-time component of the gluon propagator which corresponds to the color-Coulomb potential in the continuum limit diverges stronger than the simple pole. Furthermore, we observe that the ghost propagator show good scaling while both components of the gluon propagator do not show scaling in the considered range of the lattice spacing.
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
118183371
Wilson fermions with imaginary chemical potential
It is of prime interest to understand QCD at ﬁnite temperatur e and density. The lattice QCDwith a non-zero baryon density suffers from a sign problem, where the determinant of the quarkmatrix becomes complex and Monte Carlo simulations become unavailable. Because of this, it isstill challenge to understand the QCD at ﬁnite density. Seve ral approaches have been investigatedto overcome or circumvent the sign problem: multi-parameter reweighting, canonical approaches,imaginary chemical potentials, and so on.If the chemical potential is pure imaginary µ= µ
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