著者

Aoki S. Fukugita M. Hashimoto S. Ishikawa K.-I. Ishizuka N. Iwasaki Y. Kanaya K. Kaneko T. Kuramashi Y. Okawa M. Onogi T. Tominaga S. Tsutsui N. Ukawa A. Yamada N. Yoshie T.

出版者

American Physical Society

雑誌

Physical review D (ISSN:05562821)

巻号頁・発行日

vol.64, no.11, pp.114505, 2001-11

被引用文献数

34

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We present a lattice QCD calculation of B→πlν semileptonic decay form factors in the small pion recoil momentum region. The calculation is performed on a quenched 163×48 lattice at β=5.9 with the nonrelativistic QCD action including the full 1/M terms. The form factors f1(v⋅kπ) and f2(v⋅kπ) defined in the heavy quark effective theory for which the heavy quark scaling is manifest are adopted, and we find that the 1/M correction to the scaling is small for the B meson. The dependence of the form factors on the light quark mass and on the recoil energy is found to be mild, and we use a global fit of the form factors at various quark masses and recoil energies to obtain model independent results for the physical differential decay rate. We find that the B* pole contribution dominates the form factor f+(q2) for small pion recoil energy, and obtain the differential decay rate integrated over the kinematic region q2>18 GeV2 to be

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. Nagai K. I. 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.11, pp.114506, 2001-11

被引用文献数

43 91

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We report on a calculation of BK with domain-wall fermion action in quenched QCD. Simulations are made with a renormalization group improved gauge action at β=2.6 and 2.9 corresponding to a-1≈2 and 3 GeV. Effects due to finite fifth dimensional size N5 and finite spatial size Nσ are examined in detail. Matching to the continuum operator is made perturbatively at one loop order. We obtain BK(μ=2 GeV)=0.5746(61)(191), where the first error is statistical and the second error represents an estimate of scaling violation and O(α2) errors in the renormalization factor added in quadrature, as an estimate of the continuum value in the modified minimal subtraction (MS̅ ) scheme with naive dimensional regularization. This value is consistent, albeit somewhat small, with BK(μ=2 GeV)=0.628(42) obtained by the JLQCD Collaboration using the Kogut-Susskind quark action. Results for light quark masses are also reported.

著者

Yamazaki T. Aoki S. Burkhalter R. Fukugita M. Hashimoto S. Ishizuka N. Iwasaki Y. Kanaya K. Kaneko T. Kuramashi Y. 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.1, pp.014501, 2001-11

被引用文献数

40 75

---

We apply the maximum entropy method to extract the spectral functions for pseudoscalar and vector mesons from hadron correlators previously calculated at four different lattice spacings in quenched QCD with the Wilson quark action. We determine masses and decay constants for the ground and excited states of the pseudoscalar and vector channels from the position and area of peaks in the spectral functions. We obtain the results mπ1=660(590) MeV and mρ1=1540(570) MeV for the first excited state masses, in the continuum limit of quenched QCD. We also find unphysical states that have an infinite mass in the continuum limit, and argue that they are bound states of two doublers of the Wilson quark action. If the interpretation is correct, this is the first time that the state of doublers has been identified in lattice QCD numerical simulations.

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.11, pp.114501, 2001-10

被引用文献数

24 40

---

We present a study of the topological susceptibility in lattice QCD with two degenerate flavors of dynamical quarks. The topological charge is measured on gauge configurations generated with a renormalization group improved gauge action and a mean field improved clover quark action at three values of β=6/g2 with four sea quark masses at each β. The lattice spacings at these β’s are a≈0.22, 0.16 and 0.11 fm at the physical up and down quark mass, which are fixed by the physical ρ meson mass. The study is supplemented by simulations of pure SU(3) gauge theory with the same gauge action at 5 values of β with lattice spacings 0.09 fm≲a≲0.27 fm. We employ a field-theoretic definition of the topological charge together with cooling. For the topological susceptibility in the continuum limit of pure SU(3) gauge theory we obtain χt1/4=197-16+13 MeV where the error shows statistical and systematic ones added in quadrature. In full QCD χt at heavy sea quark masses is consistent with that of pure SU(3) gauge theory. A decrease of χt toward light quark masses, as predicted by the anomalous Ward-Takahashi identity for U(1) chiral symmetry, becomes clearer for smaller lattice spacings. The cross over in the behavior of χt from heavy to light sea quark masses is discussed.

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.64, no.9, pp.097505, 2001-10

被引用文献数

12

---

We present a dynamical lattice calculation with two flavors for bottomonium states with an additional gluonic excitation. Using improved actions for the quarks and gauge fields at a lattice spacing of a≈0.1 fm, we find 10.977(61)(62) GeV for the energy of the lowest lying bb̅ g hybrid, where the first error is statistical and the second denotes the systematic uncertainty due to the determination of scale. In a parallel quenched simulation we demonstrate explicitly that vacuum polarization effects are less than 10% of the splitting with the ground state.

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

---

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

---

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

---

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

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

---

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

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 S. Fukugita M. Hashimoto S. Ishikawa K-I. Ishizuka N. Iwasaki Y. Kanaya K. Kaneko T. Kuramashi Y. Okawa M. Onogi T. Tsutsui N. Ukawa A. Yamada N. Yoshié T.

出版者

American Physical Society

雑誌

Physical review letters (ISSN:00319007)

巻号頁・発行日

vol.91, no.21, pp.212001, 2003-11

被引用文献数

63 155

---

We present an unquenched lattice calculation for the B0-B̅ 0 transition amplitude. The calculation, carried out at an inverse lattice spacing 1/a=2.22(4)  GeV, incorporates two flavors of dynamical quarks described by the O(a)-improved Wilson fermion action and heavy quarks described by nonrelativistic QCD. Particular attention is paid to the uncertainty that arises from the chiral extrapolation, especially the effect of pion loops, for light quarks, which we find could be sizable for the leptonic decay constant, whereas it is small for the B parameters. We obtain fBd=191(10)(-22+12)   MeV, fBs/fBd=1.13(3)(-2+13), BBd(mb)=0.836(27)(-62+56), BBs/BBd=1.017(16)(-17+56), and ξ=1.14(3)(-2+13), where the first error is statistical, and the second is systematic, including uncertainties due to chiral extrapolation, finite lattice spacing, heavy quark expansion, and perturbative operator matching.