著者

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

出版者

American Physical Society

雑誌

Physical review D (ISSN:05562821)

巻号頁・発行日

vol.62, no.9, pp.094501, 2000-10

被引用文献数

14 18

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We present a study for the pion decay constant fπ in the quenched approximation to lattice QCD with the Kogut-Susskind (KS) quark action, with the emphasis given to the renormalization problems. Numerical simulations are carried out at the couplings β=6.0 and 6.2 on 323×64 and 483×64 lattices, respectively. The pion decay constant is evaluated for all KS flavors via gauge invariant and noninvariant axial vector currents with the renormalization constants calculated by both the nonperturbative method and perturbation theory. We obtain fπ=89(6) MeV in the continuum limit as the best value using the partially conserved axial vector current, which requires no renormalization. From a study for the other KS flavors we find that the results obtained with the nonperturbative renormalization constants are well convergent among the KS flavors in the continuum limit, confirming restoration of SU(4)A, flavor symmetry, while perturbative renormalization still leaves an apparent flavor breaking effect even in the continuum limit.

著者

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

出版者

American Physical Society

雑誌

Physical review D (ISSN:15507998)

巻号頁・発行日

vol.70, no.11, pp.111501, 2004-12

被引用文献数

24 15

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We present a quenched lattice QCD calculation of the alpha and beta parameters of the proton decay matrix element. The simulation is carried out using the Wilson quark action at three values of the lattice spacing in the range a[approximate]0.1-0.064 fm to study the scaling violation effect. We find only mild scaling violation when the lattice scale is determined by the nucleon mass. We obtain in the continuum limit,

著者

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

出版者

American Physical Society

雑誌

Physical review D (ISSN:05562821)

巻号頁・発行日

vol.62, no.1, pp.014506, 2000-06

被引用文献数

74 95

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We present a model-independent calculation of hadron matrix elements for all dimension-6 operators associated with baryon number violating processes using lattice QCD. The calculation is performed with the Wilson quark action in the quenched approximation at β=6/g2=6.0 on a 282×48×80 lattice. Our results cover all the matrix elements required to estimate the partial lifetimes of (proton,neutron)→(π,K,η)+(ν̅ ,e+,μ+) decay modes. We point out the necessity of disentangling two form factors that contribute to the matrix element; previous calculations did not make the separation, which led to an underestimate of the physical matrix elements. With a correct separation, we find that the matrix elements have values 3–5 times larger than the smallest estimates employed in phenomenological analyses of the nucleon decays, which could give strong constraints on several GUT models. We also find that the values of the matrix elements are comparable with the tree-level predictions of the chiral Lagrangian.

著者

Shintani E. Aoki S. Ishizuka N. Kanaya K. Kikukawa Y. Kuramashi Y. Okawa M. Taniguchi Y. Ukawa A. Yoshié T.

出版者

American Physical Society

雑誌

Physical review D (ISSN:15507998)

巻号頁・発行日

vol.72, no.1, pp.014504, 2005-07

被引用文献数

47 51

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We carry out a feasibility study for the lattice QCD calculation of the neutron electric dipole moment (NEDM) in the presence of the theta term. We develop the strategy to obtain the nucleon EDM from the CP- odd electromagnetic form factor F-3 at small theta, in which NEDM is given by lim(q2 -> 0 theta)F(3)(q(2))/(2m(N)), where q is the momentum transfer and m(N) is the nucleon mass. We first derive a formula which relates F-3, a matrix element of the electromagnetic current between nucleon states, with vacuum expectation values of nucleons and/ or the current. In the expansion of theta, the parity-odd part of the nucleon- current- nucleon three-point function contains contributions not only from the parity-odd form factors but also from the parity-even form factors multiplied by the parity-odd part of the nucleon two- point function, and, therefore, the latter contribution must be subtracted to extract F-3. We then perform an explicit lattice calculation employing the domain- wall quark action with the renormalization group improved gauge action in quenched QCD at a(-1) similar or equal to 2 GeV on a 16(3) x 32 x 16 lattice. At the quark mass m(f)a = 0: 03, corresponding to m(pi)/m(rho) similar or equal to 0:63, we accumulate 730 configurations, which allow us to extract the parityodd part in both two- and three- point functions. Employing two different Dirac gamma matrix projections, we show that a consistent value for F-3 cannot be obtained without the subtraction described above. We obtain F-3(q(2) similar or equal to 0:58 GeV2)/(2m(N))= -0:024(5) e . fm for the neutron and F-3(q(2) similar or equal to 0: 58 GeV2)/(2mN) = 0:021(6)e . fm for the proton.

著者

原 和彦 金 信弘 大川 英希 佐藤 構二 受川 史彦 ATLAS Collaboration Hara K. Kim S.H. Okawa H. Sato K. Ukegawa F.

出版者

American Physical Society

雑誌

Physical Review D (ISSN:24700010)

巻号頁・発行日

vol.97, no.5, 2018-03-27

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A search for electroweak production of supersymmetric particles in scenarios with compressed mass spectra in final states with two low-momentum leptons and missing transverse momentum is presented. This search uses proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider in 2015-2016, corresponding to 36.1 tb(-1) of integrated luminosity at root s = 13 TeV. Events with same flavor pairs of electrons or muons with opposite electric charge are selected. The data are found to be consistent with the Standard Model prediction. Results are interpreted using simplified models of R-parity conserving supersymmetry in which there is a small mass difference between the masses of the produced supersymmetric particles and the lightest neutralino. Exclusion limits at 95% confidence level are set on next-to-lightest neutralino masses of up to 145 GeV for Higgsino production and 175 GeV for wino production, and slepton masses of up to 190 GeV for pair production of sleptons. In the compressed mass regime, the exclusion limits extend down to mass splittings of 2.5 GeV for Higgsino production, 2 GeV for wino production, and 1 GeV for slepton production. The results are also interpreted in the context of a radiatively-driven natural supersymmetry model with nonuniversal Higgs boson masses.

著者

原 和彦 金 信弘 大川 英希 佐藤 構二 受川 史彦 ATLAS Collaboration Hara K. Kim S.H. Okawa H. Sato K. Ukegawa F.

出版者

American Physical Society

雑誌

Physical Review D (ISSN:24700010)

巻号頁・発行日

vol.98, no.3, 2018-08-15

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Results from a search for supersymmetry in events with four or more charged leptons (electrons, muons and taus) are presented. The analysis uses a data sample corresponding to 36.1 fb(-1) of proton-proton collisions delivered by the Large Hadron Collider at root s = 13 TeV and recorded by the ATLAS detector. Four-lepton signal regions with up to two hadronically decaying taus are designed to target a range of supersymmetric scenarios that can be either enriched in or depleted of events involving the production and decay of a Z boson. Data yields are consistent with Standard Model expectations and results are used to set upper limits on the event yields from processes beyond the Standard Model. Exclusion limits are set at the 95% confidence level in simplified models of general gauge mediated supersymmetry, where Higgsino masses are excluded up to 295 GeV. In R-parity-violating simplified models with decays of the lightest supersymmetric particle to charged leptons, lower limits of 1.46, 1.06, and 2.25 TeV are placed on wino, slepton and gluino masses, respectively.

著者

原 和彦 佐藤 構二 受川 史彦 ATLAS Collaboration Kazuhiko HARA Koji SATO Fumihiko UKEGAWA

出版者

American Physical Society

雑誌

Physical review D (ISSN:24700010)

巻号頁・発行日

vol.101, no.1, 2020-01

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Combined measurements of Higgs boson production cross sections and branching fractions are presented. The combination is based on the analyses of the Higgs boson decay modes H→γγ, ZZ∗, WW∗, ττ, b¯b, μμ, searches for decays into invisible final states, and on measurements of off-shell Higgs boson production. Up to 79.8  fb−1 of proton–proton collision data collected at √s=13  TeV with the ATLAS detector are used. Results are presented for the gluon–gluon fusion and vector-boson fusion processes, and for associated production with vector bosons or top-quarks. The global signal strength is determined to be μ=1.11+0.09−0.08. The combined measurement yields an observed (expected) significance for the vector-boson fusion production process of 6.5σ (5.3σ). Measurements in kinematic regions defined within the simplified template cross section framework are also shown. The results are interpreted in terms of modifiers applied to the Standard Model couplings of the Higgs boson to other particles, and are used to set exclusion limits on parameters in two-Higgs-doublet models and in the simplified minimal supersymmetric Standard Model. No significant deviations from Standard Model predictions are observed.

著者

Aidala C. Akiba Y. Alfred M. Andrieux V. Apadula N. Asano H. Azmoun B. Babintsev V. Bandara N. S. Barish K. N. Bathe S. Bazilevsky A. Beaumier M. Belmont R. Berdnikov A. Berdnikov Y. Blau D. S. Bok J. S. Brooks M. L. Bryslawskyj J. Bumazhnov V. Campbell S. Canoa Roman V. Cervantes R. Chi C. Y. Chiu M. Choi I. J. Choi J. B. Citron Z. Connors M. Cronin N. Csanád M. Csörgő T. Danley T. W. Daugherity M. S. David G. DeBlasio K. Dehmelt K. Denisov A. Deshpande A. Desmond E. J. Dion A. Dixit D. Do J. H. Drees A. Drees K. A. Durham J. M. Durum A. Enokizono A. En'yo H. Esumi S. Fadem B. Fan W. Feege N. Fields D. E. Finger M. Finger M. Fokin S. L. Frantz J. E. Franz A. Frawley A. D. Fukuda Y. Gal C. Gallus P. Gamez E. A. Garg P. Ge H. Giordano F. Goto Y. Grau N. Greene S. V. Grosse Perdekamp M. Gunji T. Guragain H. Hachiya T. Haggerty J. S. Hahn K. I. Hamagaki H. Hamilton H. F. Han S. Y. Hanks J. Hasegawa S. Haseler T. O. S. He X. Hemmick T. K. Hill J. C. Hill K. Hodges A. Hollis R. S. Homma K. Hong B. Hoshino T. Hotvedt N. Huang J. Huang S. Imai K. Inaba M. Iordanova A. Isenhower D. Ishimaru S. Ivanishchev D. Jacak B. V. Jezghani M. Ji Z. Jiang X. Johnson B. M. Jouan D. Jumper D. S. Kang J. H. Kapukchyan D. Karthas S. Kawall D. Kazantsev A. V. Khachatryan V. Khanzadeev A. Kim C. Kim E.-J. Kim M. Kincses D. Kistenev E. Klatsky J. Kline P. Koblesky T. Kotov D. Kudo S. Kurgyis B. Kurita K. Kwon Y. Lajoie J. G. Lebedev A. Lee S. Lee S. H. Leitch M. J. Leung Y. H. Lewis N. A. Li X. Lim S. H. Liu M. X. Loggins V.-R. Lökös S. Lovasz K. Lynch D. Majoros T. Makdisi Y. I. Makek M. Manko V. I. Mannel E. McCumber M. McGaughey P. L. McGlinchey D. McKinney C. Mendoza M. Metzger W. J. Mignerey A. C. Milov A. Mishra D. K. Mitchell J. T. Mitrankov Iu. Mitsuka G. Miyasaka S. Mizuno S. Montuenga P. Moon T. Morrison D. P. Morrow S. I. Murakami T. Murata J. Nagai K. Nagashima K. Nagashima T. Nagle J. L. Nagy M. I. Nakagawa I. Nakano K. Nattrass C. Nelson S. Niida T. Nishitani R. Nouicer R. Novák T. Novitzky N. Nyanin A. S. O'Brien E. Ogilvie C. A. Orjuela Koop J. D. Osborn J. D. Oskarsson A. Ottino G. J. Ozawa K. Pantuev V. Papavassiliou V. Park J. S. Park S. Pate S. F. Patel M. Peng W. Perepelitsa D. V. Perera G. D. N. Peressounko D. Yu. PerezLara C. E. Perry J. Petti R. Phipps M. Pinkenburg C. Pisani R. P. Pun A. Purschke M. L. Radzevich P. V. Read K. F. Reynolds D. Riabov V. Riabov Y. Richford D. Rinn T. Rolnick S. D. Rosati M. Rowan Z. Runchey J. Safonov A. S. Sakaguchi T. Sako H. Samsonov V. Sarsour M. Sato S. Scarlett C. Y. Schaefer B. Schmoll B. K. Sedgwick K. Seidl R. Sen A. Seto R. Sexton A. Sharma D. Shein I. Shibata T.-A. Shigaki K. Shimomura M. Shioya T. Shukla P. Sickles A. Silva C. L. Silvermyr D. Singh B. K. Singh C. P. Singh V. Skoby M. J. Slunečka M. Smith K. L. Snowball M. Soltz R. A. Sondheim W. E. Sorensen S. P. Sourikova I. V. Stankus P. W. Stoll S. P. Sugitate T. Sukhanov A. Sumita T. Sun J. Sun Z. Suzuki S. Sziklai J. Tanida K. Tannenbaum M. J. Tarafdar S. Taranenko A. Tarnai G. Tieulent R. Timilsina A. Todoroki T. Tomášek M. Towell C. L. Towell R. S. Tserruya I. Ueda Y. Ujvari B. van Hecke H. W. Velkovska J. Virius M. Vrba V. Vukman N. Wang X. R. Wang Z. Watanabe Y. S. Wong C. P. Woody C. L. Xu C. Xu Q. Xue L. Yalcin S. Yamaguchi Y. L. Yamamoto H. Yanovich A. Yoo J. H. Yoon I. Yu H. Yushmanov I. E. Zajc W. A. Zelenski A. Zhai Y. Zharko S. Zou L.

出版者

American Physical Society (APS)

雑誌

Physical Review D (ISSN:24700010)

巻号頁・発行日

no.99, 2019-05-13

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Measurements of the differential production of electrons from open-heavy-flavor hadrons with charm- and bottom-quark content in p+p collisions at √s=200 GeV are presented. The measurements proceed through displaced-vertex analyses of electron tracks from the semileptonic decay of charm and bottom hadrons using the PHENIX silicon-vertex detector. The relative contribution of electrons from bottom decays to inclusive heavy-flavor-electron production is found to be consistent with fixed-order-plus-next-to-leading-log perturbative-QCD calculations within experimental and theoretical uncertainties. These new measurements in p+p collisions provide a precision baseline for comparable forthcoming measurements in A+A collisions.

著者

Kiuchi Kenta Kyutoku Koutarou Sekiguchi Yuichiro Shibata Masaru Wada Tomohide

出版者

American Physical Society

雑誌

Physical Review D (ISSN:15507998)

巻号頁・発行日

vol.90, no.4, 2014-08-28

被引用文献数

166

---

連星中性子星の合体とブラックホールの進化過程に新解釈 -スーパーコンピュータ「京」で磁場の増幅機構が明らかに-. 京都大学プレスリリース. 2014-09-01.We perform high-resolution magnetohydrodynamics simulations of binary neutron star mergers in numerical relativity on the Japanese supercomputer K. The neutron stars and merger remnants are covered by a grid spacing of 70 m, which yields the highest-resolution results among those derived so far. By an in-depth resolution study, we clarify several amplification mechanisms of magnetic fields during the binary neutron star merger for the first time. First, the Kelvin-Helmholtz instability developed in the shear layer at the onset of the merger significantly amplifies the magnetic fields. A hypermassive neutron star (HMNS) formed after the merger is then subject to the nonaxisymmetric magnetorotational instability, which amplifies the magnetic field in the HMNS. These two amplification mechanisms cannot be found with insufficient-resolution runs. We also show that the HMNS eventually collapses to a black hole surrounded by an accretion torus which is strongly magnetized at birth.

著者

Seuster R. Abe K. Aihara H. Asano Y. Aushev T. Bakich A. M. Barbero M. Bedny I. Bitenc U. Bizjak I. Bozek A. Dragic J. Drutskoy A. Eidelman S. Fang F. Gershon T. Go A. Gokhroo G. Golob B. Gorišek A. Hayasaka K. Kim H. J. Hazumi M. Hoshi Y. Hou S. Hou W. -S. Iijima T. Ikado K. Itoh R. Iwasaki Y. Kang J. H. Kang J. S. Kim S. M. Kapusta P. Katayama N. Kawai H. Kawasaki T. Khan H. R. Kichimi H. Križan P. Krokovny P. Kulasiri R. Kuo C. C. Kuzmin A. Kwon Y. -J. Lange J. S. Lesiak T. Okuno S. Li J. Lin S. -W. Mandl F. Mitaroff W. Miyake H. Miyazaki Y. Mizuk R. Nagamine T. Nagasaka Y. Nakano E. Olsen S. L. Nakao M. Nishida S. Nitoh O. Ogawa S. Ohshima T. Okabe T. Onuki Y. Ozaki H. Pakhlov P. Palka H. Park C. W. Park H. Park K. S. Pestotnik R. Takasaki F. Piilonen L. E. Sakai Y. Sato N. Schietinger T. Schneider O. Schümann J. Schwanda C. Sevior M. E. Shibuya H. Sidorov V. Tamai K. Somov A. Soni N. Stamen R. Stanič S. Starič M. Suzuki S. Y. Tamura N. Tanaka M. Taylor G. N. Teramoto Y. Tian X. C. Uehara S. Uglov T. Ueno K. Bračko M. Uno S. Urquijo P. Varner G. Wang C. C. Wang C. H. Wang M. -Z. Xie Q. L. Yabsley B. D. Yamaguchi A. Yamashita Y. Brodzicka J. Yamauchi M. Ying J. Yusa Y. Zhang L. M. Zhang Z. P. Zhilich V. Chen A. Cheon B. G. Choi Y. Chuvikov A. Cole S. Dalseno J. Danilov M. Dash M. Dong L. Y.

出版者

The American Physical Society

雑誌

PHYSICAL REVIEW D (ISSN:15507998)

巻号頁・発行日

vol.73, no.32002, pp.1-22, 2006

被引用文献数

70

著者

Kiuchi Kenta Kyutoku Koutarou Sekiguchi Yuichiro Shibata Masaru Wada Tomohide

出版者

American Physical Society

雑誌

Physical Review D (ISSN:15507998)

巻号頁・発行日

vol.90, no.4, 2014-08-28

被引用文献数

166

---

連星中性子星の合体とブラックホールの進化過程に新解釈 -スーパーコンピュータ「京」で磁場の増幅機構が明らかに-. 京都大学プレスリリース. 2014-09-01.

著者

Ohki H. Takeda K. Aoki S. Hashimoto S. Kaneko T. Matsufuru H. Noaki J. Onogi T.

出版者

American Physical Society

雑誌

Physical review D (ISSN:15507998)

巻号頁・発行日

vol.87, no.3, pp.034509, 2013-02

被引用文献数

61

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We calculate the strange quark content of the nucleon ⟨N

著者

Aoki Sinya Charron Bruno Doi Takumi Hatsuda Tetsuo Inoue Takashi Ishii Noriyoshi

出版者

American Physical Society

雑誌

Physical review D (ISSN:15507998)

巻号頁・発行日

vol.87, no.3, pp.034512, 2013-02

被引用文献数

34 9

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We construct energy-independent but nonlocal potentials above inelastic thresholds, in terms of Nambu-Bethe-Salpeter wave functions defined in quantum field theories such as QCD. As an explicit example, we consider NN→NN+nπ scattering processes for n=0,1,2,…. We show the existence of energy-independent coupled channel potentials with a nonrelativistic approximation, where momenta of all particles are small compared with their own masses. In the case of two-body inelastic scatterings such as ΛΛ→ΛΛ, NΞ, ΣΣ, on the other hand, we show that energy-independent potentials can be constructed without relying on nonrelativistic approximations. We also propose a method to extract these potentials using time dependence of general correlation functions.

著者

Aoki Sinya Fukaya Hidenori Hashimoto Shoji Onogi Tetsuya

出版者

American Physical Society

雑誌

Physical review D (ISSN:15507998)

巻号頁・発行日

vol.76, no.5, pp.054508, 2007-09

被引用文献数

85 93

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In finite volume the partition function of QCD with a given theta is a sum of different topological sectors with a weight primarily determined by the topological susceptibility. If a physical observable is evaluated only in a fixed topological sector, the result deviates from the true expectation value by an amount proportional to the inverse space-time volume 1/V. Using the saddle point expansion, we derive formulas to express the correction due to the fixed topological charge in terms of a 1/V expansion. Applying this formula, we propose a class of methods to determine the topological susceptibility in QCD from various correlation functions calculated in a fixed topological sector.

著者

Aoki S. Fukugita M. Ishikawa K-I. Ishizuka N. Iwasaki Y. Kanaya K. Kaneko T. Kuramashi Y. Okawa M. Ukawa A. Yamazaki T. Yoshié T.

出版者

American Physical Society

雑誌

Physical review D (ISSN:15507998)

巻号頁・発行日

vol.71, no.9, pp.094504, 2005-05

被引用文献数

68

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We calculate the two-pion wave function in the ground state of the I=2 S-wave system and find the interaction range between two pions, which allows us to examine the validity of the necessary condition for the finite-volume method for the scattering length proposed by Lüscher. We work in the quenched approximation employing a renormalization group improved gauge action for gluons and an improved Wilson action for quarks at 1/a=1.207(12) GeV on 163×80, 203×80, and 243×80 lattices. We conclude that the necessary condition is satisfied within the statistical errors for the lattice sizes L>=24 (3.92 fm) when the quark mass is in the range that corresponds to mpi2=0.273–0.736 GeV2. We obtain the scattering length with a smaller statistical error from the wave function than from the two-pion time correlator.

著者

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

出版者

American Physical Society

雑誌

Physical review D (ISSN:15507998)

巻号頁・発行日

vol.71, no.5, pp.054505, 2005-03

被引用文献数

16 19

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We perform a nonperturbative determination of the O(a)-improvement coefficient cSW for the Wilson quark action in three-flavor QCD with the plaquette gauge action. Numerical simulations are carried out in a range of beta=12.0–5.2 on a single lattice size of 83×16 employing the Schrödinger functional setup of lattice QCD. As our main result, we obtain an interpolation formula for cSW and the critical hopping parameter Kc as a function of the bare coupling. This enables us to remove the O(a) scaling violation from physical observables in future numerical simulation in the wide range of beta. Our analysis with a perturbatively modified improvement condition for cSW suggests that finite volume effects in cSW are not large on the 83×16 lattice. We investigate Nf dependence of cSW by additional simulations for Nf=4, 2, and 0 at beta=9.6. As a preparatory step for this study, we also determine cSW in two-flavor QCD at beta=5.2. At this beta, several groups have carried out large-scale calculations of the hadron spectrum, while no systematic determination of cSW has been performed.

著者

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

出版者

American Physical Society

雑誌

Physical review D (ISSN:15507998)

巻号頁・発行日

vol.71, no.5, pp.054505, 2005-03

被引用文献数

16 19

---

We perform a nonperturbative determination of the O(a)-improvement coefficient cSW for the Wilson quark action in three-flavor QCD with the plaquette gauge action. Numerical simulations are carried out in a range of beta=12.0–5.2 on a single lattice size of 83×16 employing the Schrödinger functional setup of lattice QCD. As our main result, we obtain an interpolation formula for cSW and the critical hopping parameter Kc as a function of the bare coupling. This enables us to remove the O(a) scaling violation from physical observables in future numerical simulation in the wide range of beta. Our analysis with a perturbatively modified improvement condition for cSW suggests that finite volume effects in cSW are not large on the 83×16 lattice. We investigate Nf dependence of cSW by additional simulations for Nf=4, 2, and 0 at beta=9.6. As a preparatory step for this study, we also determine cSW in two-flavor QCD at beta=5.2. At this beta, several groups have carried out large-scale calculations of the hadron spectrum, while no systematic determination of cSW has been performed.

著者

Namekawa Y. Aoki S. Fukugita M. Ishikawa K.-I. Ishizuka N. Iwasaki Y. Kanaya K. Kaneko T. Kuramashi Y. Lesk V. I. Okawa M. Ukawa A. Umeda T. Yoshié T.

出版者

American Physical Society

雑誌

Physical review D (ISSN:15507998)

巻号頁・発行日

vol.70, no.7, pp.074503, 2004-10

被引用文献数

24 31

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We extend the study of the light hadron spectrum and the quark mass in two-flavor QCD to smaller sea quark mass, corresponding to mPS/mV=0.60–0.35. Numerical simulations are carried out using the RG-improved gauge action and the meanfield-improved clover quark action at beta=1.8 (a=0.2 fm from rho meson mass). We observe that the light hadron spectrum for small sea quark mass does not follow the expectation from chiral extrapolations with quadratic functions made from the region of mPS/mV=0.80–0.55. Whereas fits with either polynomial or continuum chiral perturbation theory (ChPT) fail, the Wilson ChPT (WChPT) that includes a2 effects associated with explicit chiral symmetry breaking successfully fits the whole data: In particular, WChPT correctly predicts the light quark mass spectrum from simulations for medium heavy quark mass, such as mPS/mV>~0.5. Reanalyzing the previous data with the use of WChPT, we find the mean up and down quark mass being smaller than the previous result from quadratic chiral extrapolation by approximately 10%, mudMS-bar(µ=2 GeV)=3.11(17) [MeV] in the continuum limit.

著者

Yamazaki T. Aoki S. Fukugit M. Ishikawa K-I. 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:15507998)

巻号頁・発行日

vol.70, no.7, pp.074513, 2004-10

被引用文献数

82 94

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We present a lattice QCD calculation of phase shift including the chiral and continuum extrapolations in two-flavor QCD. The calculation is carried out for I=2 S-wave pipi scattering. The phase shift is evaluated for two momentum systems, the center of mass and laboratory systems, by using the finite-volume method proposed by Lüscher in the center of mass system and its extension to general systems by Rummukainen and Gottlieb. The measurements are made at three different bare couplings beta=1.80, 1.95 and 2.10 using a renormalization group improved gauge and a tadpole improved clover fermion action, and employing a set of configurations generated for hadron spectroscopy in our previous work. The illustrative values we obtain for the phase shift in the continuum limit are delta(deg.)=-3.50(64), -9.5(30) and -16.9(64) for sqrt(s)(GeV)=0.4, 0.6 and 0.8, which are consistent with experiments.

著者

Takeda S. Aoki S. Fukugita M. Ishikawa K-I. 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:15507998)

巻号頁・発行日

vol.70, no.7, pp.074510, 2004-10

被引用文献数

16 23

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We study the scaling behavior of the step scaling function for SU(3) gauge theory, employing the renormalization-group improved Iwasaki gauge action and the perturbatively improved Lüscher-Weisz gauge action. We confirm that the step scaling functions from the improved gauge actions agree with that previously obtained from the plaquette action within errors in the continuum limit at both weak and strong coupling regions. We also investigate how different choices of boundary counterterms for the improved gauge actions affect the scaling behavior. In the extrapolation to the continuum limit, we observe that the cutoff dependence becomes moderate for the Iwasaki action, if a perturbative reduction of scaling violations is applied to the simulation results. We also measure the low energy scale ratio with the Iwasaki action and confirm its universality.