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Takuya Saito

Publications and source records attributed to Takuya Saito.

42 records · Page 3Linked to original sources
arXiv2004

Long-distance behavior of $q\bar{q}$ color dependent potentials at finite temperature

SU(3) heavy quark potentials at finite temperature are studied with quenched lattice QCD using the stochastic gauge-fixing method. In addition to the standard color average channel, we investigate $q\bar{q}$ potentials in singlet and octet channels. % We obtain clear signals in all cases. The singlet $q\bar{q}$ channel yields an attractive force, while the octet $q\bar{q}$ potential is repulsive; the corresponding color average channel also results in an attractive force. %As the temperature increases, these forces are weakened and As the temperature increases, these forces become weak and their variations are very small; at $T/T_c=1.8-5.6$, % the singlet attractive force is not so weakened even for long distances. the singlet attractive force survives over $R \sim 1/T$. The singlet and octet potentials calculated with this algorithm have a small gauge dependence when the gauge parameter $α$ is changed from 0.6 to 1.3.

hep-lat↗
arXiv2001

Anisotropic Lattice and Its Application to Quark Gluon Plasma

We have studied the link-integration method for the improved actions. With this method the $η$ parameter in the medium to strong coupling regions is obtained. Effects of the self-energy terms for the $η$ parameters are small in the regions of $β$ and $η$ studied. After these investigations, the anisotropic lattice is used for the calculation of transport coefficients of the quark gluon plasma.

hep-lat↗
arXiv2000

Anisotropic Improved Actions

The studies of the quantum corrections for the anisotropy parameter,$η(=ξ_R/ξ_B)$, for the improved actions, $β(C_0 L({Plaq.}) + C_1 L({Rect.}))$, 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 $C_{1}$ have been clarified. It has been found by the perturbative analysis that as $C_1$ decreases, the slope of the $η(β)$ becomes less steep and for the actions whose $C_{1}$ 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 $C_{1}$. This means that for the actions with $C_{1} < -0.160$, 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 $β$.

hep-lat↗
arXiv1998

Anisotropic Improved Gauge Actions; --Perturbative and Numerical Studies --

The $Λ$ parameter on the anisotropic lattice, the spatial and temperature coupling constant $g_σ$, $g_τ$ and their derivative with respaect to the the anisotropy parameter $ξ$ are studied perturbatively for the class of improved actions, which cover tree level Symanzik's, Iwasaki's and QCDTARO's improved actions. The $η(=g_τ/g_σ)$ becomes less than 1 for Iwasaki's and QCDTARO's action, which is confirmed nonperturbatively by numerical simulations. Derivatives of the coupling constants with respect to the anisotropy parameter, $\partial g_τ/\partial ξ$ and $\partial g_σ/\partial ξ$, change sign for those improved actions.

hep-lat↗
arXiv1998

Transport Coefficients of Quark Gluon Plasma From Lattice Gauge Theory

Numerical results for the transport coefficients of quark gluon plasma are obtained by lattice simulations on on $16^3 \times 8$ lattice with the quench approximation where we apply the gauge action proposed by Iwasaki. The bulk viscosity is consistent with zero, and the shear viscosity is slightly smaller than the typical hadron masses. They are not far from the simple extrapolation on the figure of perturbative calculation in high temperature limit down to $T \sim T_{c}$. The gluon propagator in the confined and deconfined phases are also discussed.

hep-lat↗