著者

Okamoto M. Aoki S. Burkhalter R. Ejiri S. Fukugita M. Hashimoto S. Ishikawa K-I. Ishizuka N. Iwasaki Y. Kanaya K. Kaneko T. Kuramashi Y. Lesk V. Nagai K. Okawa M. Taniguchi Y. Ukawa A. Yoshié T.

出版者

American Physical Society

雑誌

Physical review D (ISSN:05562821)

巻号頁・発行日

vol.65, no.9, pp.094508, 2002-04

被引用文献数

91 128

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We present a detailed study of the charmonium spectrum using anisotropic lattice QCD. We first derive a tree-level improved clover quark action on the anisotropic lattice for arbitrary quark mass by matching the Hamiltonian on the lattice and in the continuum. The heavy quark mass dependence of the improvement coefficients, i.e., the ratio of the hopping parameters ζ=Kt/Ks and the clover coefficients cs,t, is examined at the tree level, and effects of the choice of the spatial Wilson parameter rs are discussed. We then compute the charmonium spectrum in the quenched approximation employing ξ=as/at=3 anisotropic lattices. Simulations are made with the standard anisotropic gauge action and the anisotropic clover quark action with rs=1 at four lattice spacings in the range as=0.07–0.2 fm. The clover coefficients cs,t are estimated from tree-level tadpole improvement. On the other hand, for the ratio of the hopping parameters ζ, we adopt both the tree-level tadpole-improved value and a non-perturbative one. The latter employs the condition that the speed of light calculated from the meson energy-momentum relation be unity. We calculate the spectrum of S and P states and their excitations using both the pole and kinetic masses. We find that the combination of the pole mass and the tadpole-improved value of ζ to yield the smoothest approach to the continuum limit, which we then adopt for the continuum extrapolation of the spectrum. The results largely depend on the scale input even in the continuum limit, showing a quenching effect. When the lattice spacing is determined from the 1P-1S splitting, the deviation from the experimental value is estimated to be ∼30% for the S-state hyperfine splitting and ∼20% for the P-state fine structure. Our results are consistent with previous results at ξ=2 obtained by Chen when the lattice spacing is determined from the Sommer scale r0. We also address the problem with the hyperfine splitting that different choices of the clover coefficients lead to disagreeing results in the continuum limit. Making a leading order analysis based on potential models we show that a large hyperfine splitting ∼95 MeV obtained by Klassen with a different choice of the clover coefficients is likely an overestimate.

著者

Namekawa Y. Aoki S. Burkhalter R. Ejiri S. Fukugita M. Hashimoto S. Ishizuka N. Iwasaki Y. Kanaya K. Kaneko T. Kuramashi Y. Lesk V. Okamoto M. Okawa M. Taniguchi Y. Ukawa A. Yoshié T.

出版者

American Physical Society

雑誌

Physical review D (ISSN:05562821)

巻号頁・発行日

vol.64, no.7, pp.074507, 2001-09

被引用文献数

36 50

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Finite temperature SU(3) gauge theory is studied on anisotropic lattices using the standard plaquette gauge action. The equation of state is calculated on 163×8, 203×10, and 243×12 lattices with the anisotropy ξ≡as/at=2, where as and at are the spatial and temporal lattice spacings. Unlike the case of the isotropic lattice on which Nt=4 data deviate significantly from the leading scaling behavior, the pressure and energy density on an anisotropic lattice are found to satisfy well the leading 1/Nt2 scaling from our coarsest lattice Nt/ξ=4. With three data points at Nt/ξ=4, 5 and 6, we perform a well controlled continuum extrapolation of the equation of state. Our results in the continuum limit agree with a previous result from isotropic lattices using the same action, but have smaller and more reliable errors.

著者

Khan A. Ali Aoki S. Burkhalter R. Ejiri S. Fukugita M. Hashimoto S. Ishizuka N. Iwasaki Y. Kanaya K. Kaneko T. Kuramashi Y. Manke T. Nagai K.-I. Okamoto M. Okawa M. Shanahan H. P. Taniguchi Y. Ukawa A. Yoshié T.

出版者

American Physical Society

雑誌

Physical review D (ISSN:05562821)

巻号頁・発行日

vol.64, no.7, pp.074510, 2001-09

被引用文献数

91

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We present the results of a first study of the equation of state in finite-temperature QCD with two flavors of Wilson-type quarks. The simulations are made on lattices with a temporal size Nt=4 and 6, using a renormalization-group-improved action for the gluon sector and a mean-field-improved clover action for the quark sector. The lines of constant physics corresponding to fixed values of the ratio mPS/mV of the pseudoscalar to vector meson masses at zero temperature are determined, and the beta functions which describe the renormalization-group flow along these lines are calculated. Using these results, the energy density and the pressure are calculated as functions of temperature along the lines of constant physics in the range mPS/mV=0.65–0.95. The quark mass dependence in the equation of state is found to be small for mPS/mV≲0.8. A comparison of the results for Nt=4 and Nt=6 lattices shows a significant scaling violation present in the Nt=4 results. At high temperatures the results for Nt=6 are quite close to the continuum Stefan-Boltzmann limit, suggesting the possibility of a precise continuum extrapolation of thermodynamic quantities from simulations at Nt≳6.

著者

Okamoto M. Khan A. Ali Aoki S. Burkhalter R. Ejiri S. Fukugita M. Hashimoto S. Ishizuka N. Iwasaki Y. Kanaya K. Kaneko T. Kuramashi Y. Manke T. Nagai K. Okawa M. Ukawa A. Yoshié T.

出版者

American Physical Society

雑誌

Physical review D (ISSN:05562821)

巻号頁・発行日

vol.60, no.9, pp.094510, 1999-10

被引用文献数

104 166

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A lattice study of the equation of state for pure SU(3) gauge theory using a renormalization-group (RG) improved action is presented. The energy density and pressure are calculated on a 163×4 and a 323×8 lattice employing the integral method. Extrapolating the results to the continuum limit, we find the energy density and pressure to be in good agreement with those obtained with the standard plaquette action within the error of 3–4 %.