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

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

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

165

---

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

165

---

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

---

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

32 9

---

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

83 93

---

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

---

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

---

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

---

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

---

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

---

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.

著者

Aoki S. Fukugita M. 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.3, pp.034503, 2004-08

被引用文献数

4

---

We report on a nonperturbative evaluation of the renormalization factors for the vector and axial-vector currents, ZV and ZA, in the quenched domain-wall QCD (DWQCD) with plaquette and renormalization-group-improved gauge actions. We take the Dirichlet boundary condition for both gauge and domain-wall fermion fields on the finite box, and introduce flavor-chiral Ward-Takahashi identities to calculate the renormalization factors. As a test of the method, we numerically confirm the expected relation that ZV~=ZA in DWQCD. Employing two different box sizes for the numerical simulations at several values of the gauge coupling constant g2 and the domain-wall height M, we extrapolate ZV to infinite volume to remove a/L errors. We finally give the interpolation formula of ZV in the infinite volume as a function of g2 and M.

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

---

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

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

---

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

Aoki Sinya Nagai Kei-ichi Taniguchi Yusuke Ukawa Akira

出版者

American Physical Society

雑誌

Physical review.D (ISSN:15507998)

巻号頁・発行日

vol.58, no.7, pp.074505, 1998-10

被引用文献数

44 90

---

We calculate one-loop renormalization factors of bilinear quark operators for the gluon action includingsix-link loops and an O(a)-improved quark action in the limit of a massless quark. We find that finite parts ofthe one-loop coefficients of renormalization factors diminish monotonically as either of the coefficients c1 orc21c3 of the six-link terms is decreased below zero. Detailed numerical results are given, for general valuesof the clover coefficient, for the tree-level improved gluon action in the Symanzik approach (c1521/12,c25c350) and for the choices suggested by Wilson (c1520.252,c250,c3520.17) and by Iwasaki (c1520.331,c25c350 and c1520.27,c21c3520.04) from renormalization-group analyses. Compared with thecase of the standard plaquette gluon action, the finite parts of the one-loop coefficients are reduced by 10–20 %for the Symanzik action, and approximately by a factor of 2 for the renormalization-group improved gluonactions.

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

---

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.