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

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. Shanahan H. P. 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.5, pp.054504, 2001-08

被引用文献数

34 81

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We present a study of leptonic B meson decay constants in lattice QCD with two flavors (Nf=2) of light dynamical quarks using nonrelativistic QCD for the heavy quark. Gauge configurations are generated with a renormalization-group improved gauge action and a mean-field-improved clover light quark action. Measurements are carried out at two values of β=6/g2, each for four sea quark masses, corresponding to inverse lattice spacings a-1≈1.3 and 1.8 GeV in the chiral limit of the sea quark. The continuum values of the decay constants are derived by evaluating the discretization errors at each finite lattice spacing. We find fBNf=2=204(8)(29)(+44) MeV, fBsNf=2=242(9)(34)(+38) MeV, and fBsNf=2/fBNf=2=1.179(18)(23), where the errors listed are statistical, systematic and uncertainty due to choice of the physical quantity used to fix the scale. Comparison is made to quenched results (Nf=0) obtained with the same action combination and matching lattice spacings. We find fBNf=2/fBNf=0=1.07(5), fBsNf=2/fBsNf=0=1.10(5) and (fBs/fB)Nf=2/(fBs/fB)Nf=0=1.03(2), which indicate a 5–10 % increase in the values of the decay constants, but no appreciable change in the ratio fBs/fB, due to sea quarks.

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. Okawa M. Shanahan H. P. 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.3, pp.034505, 2001-07

被引用文献数

30 98

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We present a calculation of the B and D meson decay constants in lattice QCD with two (Nf=2) flavors of light dynamical quarks, using an O(a)-improved Wilson action for both light and heavy quarks and a renormalization-group improved gauge action. Simulations are made at three values of lattice spacing a=0.22,0.16,0.11 fm and four values of sea quark mass in the range mPS/mV≈0.8-0.6. Our provisional estimate for the continuum values of the decay constants are fBd=208(10)(29) MeV, fBs=250(10)(35)(-0+8) MeV, fDd=225(14)(40) MeV, fDs=267(13)(48)(-0+10) MeV for Nf=2 where the statistical and systematic errors are separately listed, and the third error for fBs and fDs shows the uncertainty of the determination of the strange quark mass. We also carry out a set of quenched simulations using the same action to make a direct examination of sea quark effects. Taking the ratio of results for Nf=2 and Nf=0, we obtain fBdNf=2/fBdNf=0=1.11(6),fBsNf=2/fBsNf=0=1.14(5),fDdNf=2/fDdNf=0=1.03(6),fDsNf=2/fDsNf=0=1.07(5). They show a 10–15 % increase in the Nf=2 results over those of Nf=0 for the B meson decay constants, while evidence for such a trend is statistically less clear for the D meson decay constants.

著者

Khan A. Ali Aoki S. Aoki Y. Burkhalter R. Ejiri S. Fukugita M. Hashimoto S. Ishizuka N. Iwasaki Y. Izubuchi T. Kanaya K. Kaneko T. Kuramashi Y. Manke T. Nagai K. I. Noaki J. 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.63, no.11, pp.114504, 2001-05

被引用文献数

47 61

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We investigate the chiral properties of quenched domain-wall QCD (DWQCD) at the lattice spacings a-1≃1 and 2 GeV for both plaquette and renormalization-group (RG) improved gauge actions. In the case of the plaquette action we find that the quark mass defined through the axial Ward-Takahashi identity remains non-vanishing in the DWQCD chiral limit that the bare quark mass mf→0 and the length of the fifth dimension Ns→∞, indicating that chiral symmetry is not realized with quenched DWQCD up to a-1≃2 GeV. The behavior is much improved for the RG-improved gauge action: while a nonvanishing quark mass remains in the chiral limit at a-1≃1 GeV, the result at a-1≃2 GeV is consistent with an exponentially vanishing quark mass in the DWQCD chiral limit, indicating the realization of exact chiral symmetry. An interpretation and implications are briefly discussed.

著者

Taniguchi Yusuke

出版者

American Physical Society

雑誌

Physical review D (ISSN:05562821)

巻号頁・発行日

vol.63, no.1, pp.014502, 2000-12

被引用文献数

24 31

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The one loop correction to the SUSY Ward-Takahashi identity is calculated on the lattice with a Wilson fermion. The supersymmetry on the lattice is broken explicitly by the gluino mass and the lattice artifact. We should fine-tune the parameters in the theory to the point given by the additive mass correction in order to eliminate the breaking effect of the lattice artifact. It is shown that the additive mass correction appearing from the SUSY Ward-Takahashi identity coincide with that from the axial U(1)R symmetry, as suggested by Curci and Veneziano. Two important symmetries of the super Yang-Mills theory can be recovered simultaneously in the continuum with a single fine-tuning. The operator mixing of the supercurrent is also investigated. We find that the supercurrent mixes only with a gauge-invariant current Tμ which is related to the gamma-trace anomaly.

著者

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

出版者

American Physical Society

雑誌

Physical review D (ISSN:05562821)

巻号頁・発行日

vol.62, no.11, pp.114508, 2000-11

被引用文献数

32

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We study the effects of two dynamical sea quarks on the spectrum of heavy quarkonia. Within the non-relativistic approach to lattice QCD we find sizable changes to the hyperfine splitting, but we do not observe any changes for the fine structure. We also investigate the scaling behavior of our results for several different lattice spacings.

著者

Ishikawa K-I. Yamada N. Aoki S. Fukugita M. Hashimoto S. Ishizuka N. Iwasaki Y. Kanaya K. Kaneda T. Kaya S. Kuramashi Y. Matsufuru H. Okawa M. Onogi T. Tominaga S. Tsutsui N. Ukawa A. Yoshié T.

出版者

American Physical Society

雑誌

Physical review D (ISSN:05562821)

巻号頁・発行日

vol.61, no.7, pp.074501, 2000-02

被引用文献数

27 72

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We present a lattice NRQCD study of the B meson decay constant in the quenched approximation with emphasis given to the scaling behavior. The NRQCD action and the heavy-light axial vector current we use include all terms of order 1/M and the perturbative O(αsa) and O(αs/M) corrections. Using simulations at three values of couplings β=5.7, 5.9, and 6.1 on lattices of sizes 123×32, 163×48, and 243×64, we find a significant a dependence disappears in fB if the O(αsa) correction is included in the axial vector current. We observe that β=5.9-6.1 is the window where systematic errors are expected to be minimum within one-loop improved theory. Our final results are fB=170(5)(15) MeV, fBs=191(4)(17)(-0+4) MeV, and fBs/fB=1.12(2)(1)(-0+3), where the first error is statistical, the second is systematic, and the third is due to the uncertainty of the strange quark mass, while quenching errors are not included.

著者

Aoki S. Boyd G. Burkhalter R. Hashimoto S. Ishizuka N. Iwasaki Y. Kanaya K. Kaneko T. Kuramashi Y. 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.11, pp.114508, 1999-11

被引用文献数

52 138

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We investigate the effects of action improvement on the light hadron spectrum and the static quark potential in two-flavor QCD for a-1≈1 GeV and mPS/mV=0.7–0.9. We compare a renormalization group improved action with the plaquette action for gluons and the SW-clover action with the Wilson action for quarks. We find a significant improvement in the hadron spectrum by improving the quark action, while the gluon improvement is crucial for a rotationally invariant static potential. We also explore the region of light quark masses corresponding to mPS/mV>~0.4 on a 2.7 fm lattice using the improved gauge and quark action. A flattening of the potential is not observed up to 2 fm.

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 %.

著者

Aoki Y. Csikor F. Fodor Z. Ukawa A.

出版者

American Physical Society

雑誌

Physical review D (ISSN:15507998)

巻号頁・発行日

vol.60, no.1, pp.013001, 1999-07

被引用文献数

80

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We study the first-order finite-temperature electroweak phase transition of the SU~2! gauge-Higgs modeldefined on a four-dimensional isotropic lattice with the temporal extension Nt52. A finite-size scaling study ofLee-Yang zeros yields the value of the Higgs self-coupling of the end point at lc50.00116(16). An independentanalysis of the Binder cumulant gives a consistent value for the end point. Combined with our zerotemperaturemeasurement of Higgs and W boson masses, this leads to MH,c573.366.4 GeV for the criticalHiggs boson mass beyond which the electroweak transition turns into a crossover.

著者

Aoki S. Fukugita M. Hashimoto S. Ishizuka N. Iwasaki Y. Kanaya K. Kuramashi Y. 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.3, pp.034511, 1999-07

被引用文献数

24 47

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A lattice QCD calculation of the kaon B parameter BK is carried out with the Wilson quark action in the quenched approximation at β=6/g2=5.9–6.5. The mixing problem of the Δs=2 four-quark operators is solved nonperturbatively with full use of chiral Ward identities employing four external quarks with an equal off-shell momentum in the Landau gauge. This method, without invoking any effective theory, enables us to construct the weak four-quark operators exhibiting good chiral behavior. Our results for BK with the nonperturbative mixing coefficients show small scaling violation beyond the lattice cutoff a-1∼2.5 GeV. Our estimate concludes BK(NDR,2 GeV)=0.69(7) at a-1=2.7–4.3 GeV, which agrees with the value obtained with the Kogut-Susskind quark action. For comparison we also calculate BK with one-loop perturbative mixing coefficients. While this yields incorrect values at finite lattice spacing, a linear extrapolation to the continuum limit as a function of a leads to a result consistent with those obtained with the Ward identity method.

著者

Izubuchi Taku Noaki Junichi Ukawa Akira

出版者

American Physical Society

雑誌

Physical review D (ISSN:15507998)

巻号頁・発行日

vol.58, no.11, pp.114507, 1998-12

被引用文献数

10 17

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We investigate the phase structure of the two-dimensional lattice Gross-Neveu model formulated with theWilson fermion action to leading order of 1/N expansion. The structural change of the parity-broken phaseunder the influence of finite temperature and chemical potential is studied. The connection between the latticephase structure and the chiral phase transition of the continuum theory is clarified.

著者

Ejiri S. Iwasaki Y. Kanaya K.

出版者

American Physical Society

雑誌

Physical review D (ISSN:05562821)

巻号頁・発行日

vol.58, no.9, pp.094505, 1998-10

被引用文献数

19 24

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We propose a new nonperturbative method to compute the derivatives of gauge coupling constants with respect to anisotropic lattice spacings (anisotropy coefficients), which are required in an evaluation of thermodynamic quantities from numerical simulations on the lattice. Our method is based on a precise measurement of the finite temperature deconfining transition curve in the lattice coupling parameter space extended to anisotropic lattices by applying the spectral density method. We test the method for the cases of SU(2) and SU(3) gauge theories at the deconfining transition point on lattices with the lattice size in the time direction Nt=4–6. In both cases, there is a clear discrepancy between our results and perturbative values. A long standing problem, when one uses the perturbative anisotropy coefficients, is a nonvanishing pressure gap at the deconfining transition point in the SU(3) gauge theory. Using our nonperturbative anisotropy coefficients, we find that this problem is completely resolved: we obtain Δp/T4=0.001(15) and -0.003(17) on Nt=4 and 6 lattices, respectively.

著者

Taniguchi Yusuke Ukawa Akira

出版者

American Physical Society

雑誌

Physical review D (ISSN:05562821)

巻号頁・発行日

vol.58, no.11, pp.114503, 1998-10

被引用文献数

38 60

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We calculate the O(g2a) mixing coefficients of bilinear quark operators in lattice QCD using a standard perturbative evaluation of on-shell Green’s functions. Our results for the plaquette gluon action are in agreement with those previously obtained with the Schrödinger functional method. The coefficients are also calculated for a class of improved gluon actions having six-link terms.

著者

Aoki S. Fukugita M. Hashimoto S. Ishizuka N. Iwasaki Y. Kanaya K. Kuramashi Y. 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.58, no.5, pp.054503, 1998-07

被引用文献数

13 39

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We present a calculation for the K+→π+π0 decay amplitude using a quenched simulation of lattice QCD with the Wilson quark action at β=6/g2=6.1. The decay amplitude is extracted from the ratio, the K→ππ three-point function divided by either K and π meson two-point functions or K meson two-point function and I=2 ππ four-point function; the two different methods yield consistent results. Finite size effects are examined with calculations made on 243×64 and 323×64 lattices, and are shown that they are explained by one-loop effects of chiral perturbation theory. The lattice amplitude is converted to the continuum value by employing a one-loop calculation of chiral perturbation theory, yielding a value in agreement with experiment if extrapolated to the chiral limit. We also report on the K meson B parameter BK obtained from the K+→π+π0 amplitude using chiral perturbation theory.

著者

Yamazaki Takeshi Ishikawa Ken-ichi Kuramashi Yoshinobu Ukawa Akira

出版者

American Physical Society

雑誌

Physical review D (ISSN:15507998)

巻号頁・発行日

vol.86, no.7, pp.074514, 2012-10

被引用文献数

92

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We calculate the binding energies for multinucleon bound states with the nuclear mass number less than or equal to 4 in 2+1 flavor QCD at the lattice spacing of a=0.09  fm employing a relatively heavy quark mass corresponding to mπ=0.51  GeV. To distinguish a bound state from attractive scattering states, we investigate the volume dependence of the energy shift between the ground state and the state of free nucleons by changing the spatial extent of the lattice from 2.9 to 5.8 fm. We conclude that 4He, 3He, deuteron and dineutron are bound at mπ=0.51  GeV. We compare their binding energies with those in our quenched studies and also with several previous investigations.