119191322
QCD Phase Diagram with Imaginary Chemical Potential
We report our recent results on the QCD phase diagram obtained from the lattice QCD simulation. The location of the phase boundary between hadronic and QGP phases in the two-flavor QCD phase diagram is investigated. The imaginary chemical potential approach is employed, which is based on Monte Carlo simulations of the QCD with imaginary chemical potential and analytic continuation to the real chemical potential region.
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.
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.
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.
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
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.
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