著者

Mirković J. Savel’ev S. E. Sugahara E. Kadowaki K.

出版者

American Physical Society

雑誌

Physical review B (ISSN:01631829)

巻号頁・発行日

vol.66, no.13, pp.132505, 2002-10

被引用文献数

13 12

---

The vortex-liquid and vortex-solid phases in single crystals of Bi2Sr2CaCu2O8+δ placed in tilted magnetic fields are studied by in-plane resistivity measurements using the Corbino geometry to avoid spurious surface-barrier effects. It was found that the anisotropy of the vortex-solid phase increases with temperature and exhibits a maximum at T≈0.97Tc. In contrast, the anisotropy of the vortex-liquid phase rises monotonically across the whole measured temperature range. The observed behavior is discussed in the context of dimensional crossover and thermal fluctuations of vortices in the strongly layered system.

著者

Kawano-Furukawa H. Yoshizawa H. Takeya H. Kadowaki K.

出版者

American Physical Society

雑誌

Physical review B (ISSN:01631829)

巻号頁・発行日

vol.66, no.21, pp.212503, 2002-12

被引用文献数

6 7

---

An anomalous phonon peak that appears only in the superconducting state has been reported for nonmagnetic intermetallic superconductor RNi211B2C (R=Y, Lu). In the present paper, we shall demonstrate that another rare-earth borocarbide ErNi211B2C seems to show similar phonon anomalies. A spectral weight transfer from the above-lying TA phonon mode to the aforementioned peak was rather small, but it is consistent with the theoretical prediction for the system with smaller 2Δ/Eph ratio. Combining the present results with those observed in the other borocarbide systems, we suggest that such a phonon anomaly might be a common phenomenon for superconductors with a strong nesting feature of the Fermi surface.

著者

滝川 浩郷 森 謙治 木戸 勝 Albizati K. F. Faulkner D. J.

出版者

天然有機化合物討論会実行委員会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

vol.34, pp.707-714, 1992

---

In 1985, limatulone (1a and 1b) was isolated from the intertidal limpet Collisella limatula, and found to inhibit fish and crab predation. It is the most potent fish feeding inhibitor and is about an order of magnitude more effective than polygodial. Although the natural limatulone was optically inactive, it was not clear whether it was a meso-compound (1a) or a racemate (1b). We therefore decided to confirm the structure by a total synthesis. The known 3, which was obtained from the starting material (2) in 4 steps, was alkylated with BrCH_2CO_2Et to give 4a. The corresponding acid 4b was employed for the lactone-ring formation to give a stereoisomeric mixture of lactones 5a and 5b. After separation, lactone 5a was converted to the coupling-partners 10 and 11 via 6, respectively. The carbanion derived from 11 was alkylated with 10 to give a complex mixture, which was desulfonylated with Na-Hg to give a mixture of 12a and 12b. This was converted to a separable mixture of 13a and 13b. Fortunately, the structure of the less polar isomer could be solved by an X-ray analysis. An aldehyde 15a, which was prepared from 13a in 3steps, was treated with ClCH_2Li to give bis-epoxide 16a. Epoxide-opening of 16a by a Grignard reagent gave 17a. Swern oxidation of 17a to 18a was followed by removal of the EE protective groups to give meso-limatulone (1a), (overall yield: 0.62% from 2 in 24 steps). Similarly, (±)-13b was converted to (±)-limatulone (1b), (overall yield: 0.39% from 2 in 24 steps). The ^1H-NMR spectrum of the reported limatulone was identical to that of (±)-limatulone (1b). To our surprise, however, another fraction from the HPLC of Collisella limatula showed the ^1H-NMR spectrum superimposable on that of meso-limatulone (1a). Accordingly, Collisella limatula produces both meso-1a and (±)-1b.

著者

Daugsch A. Moraes C.S. Fort P. Park Y.K.

出版者

玉川大学ミツバチ科学研究所

雑誌

ミツバチ科学 = Honeybee science (ISSN:03882217)

巻号頁・発行日

vol.27, no.2, pp.55-62, 2007-02 (Released:2011-03-05)

著者

Machida Y. Sasaki S. Fujii H. Furuyama M. Kakeya I. Kadowaki K.

出版者

American Physical Society

雑誌

Physical review B (ISSN:01631829)

巻号頁・発行日

vol.67, no.9, pp.094507, 2003-03

被引用文献数

31 37

---

We synthesized single crystalline MgB2 under ambient pressure by using conventional materials and equipment. The single crystals of MgB2 were of good quality, where the crystal structure refinements were successfully converged with R=0.020. The measurements of the magnetic properties yielded a sharp superconducting transition at 38 K with transition width ΔTc=0.8 K. The upper critical field for applied field parallel to the ab plane (Hc2ab) reveals a positive curvature, while Hc2 parallel to the c axis (Hc2c) increases linearly in temperature dependence, which yields a temperature dependence of the superconducting anisotropy ratio of γ=Hc2ab/Hc2c with γ∼1 near Tc and 4.0 at 25 K.

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

Kaminski A. Rosenkranz S. Fretwell H. M. Mesot J. Randeria M. Campuzano J. C. Norman M. R. Li Z. Z. Raffy H. Sato T. Takahashi T. Kadowaki K.

出版者

American Physical Society

雑誌

Physical review B (ISSN:01631829)

巻号頁・発行日

vol.69, pp.212509, 2004-06

被引用文献数

31 34

---

One of the interesting features of the photoemission spectra of the high temperature cuprate superconductors is the presence of a large signal (referred to as the "background") in the unoccupied region of the Brillouin zone. Here we present data indicating that the background signal is a component of the photocurrent that is separate from the spectral function and is most likely due to strong scattering of the photoelectrons. We also present an analytical method that can be used to subtract the background signal.

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

Kaminski A. Fretwell H. M. Norman M. R. Randeria M. Rosenkranz S. Chatterjee U. Campuzano J. C. Mesot J. Sato T. Takahashi T. Terashima T. Takano M. Kadowaki K. Li Z. Z. Raffy H.

出版者

American Physical Society

雑誌

Physical review B (ISSN:10980121)

巻号頁・発行日

vol.71, pp.014517, 2005-01

被引用文献数

83 80

---

We examine the momentum and energy dependence of the scattering rate of the high-temperature cuprate superconductors using angle-resolved photoemission spectroscopy. The scattering rate is of the form a + bomega around the Fermi surface for under-and optimal doping. The inelastic coefficient b is found to be isotropic. The elastic term a, however, is found to be highly anisotropic for under-and optimally doped samples, with an anisotropy which correlates with that of the pseudogap. This is contrasted with heavily overdoped samples, which show an isotropic scattering rate and an absence of the pseudogap above Tc. We find this to be a generic property for both single-and double-layer compounds.

著者

Baelus B. J. Kadowaki K. Peeters F. M.

出版者

American Physical Society

雑誌

Physical review B (ISSN:10980121)

巻号頁・発行日

vol.71, pp.024514, 2005-01

被引用文献数

27

---

Solving the nonlinear Ginzburg-Landau equations self-consistently we investigated the influence of surface defects on the vortex penetration and expulsion in thin mesoscopic superconducting samples. The effect of the number, size, and position of surface defects on the vortex entry and exit fields and on the entrance and exit positions of the vortex are studied for very thin circular, square, and rectangular samples. For specific vortex configurations we found that due to the interplay between the vortex-vortex repulsion and the vortex-defect interaction, the vortex does not enter or leave the sample through the surface defect.

著者

Baelus B. J. Kanda A. Peeters F. M. Ootuka Y. Kadowaki K.

出版者

American Physical Society

雑誌

Physical review B (ISSN:10980121)

巻号頁・発行日

vol.71, pp.140502, 2005-04

被引用文献数

30 29

---

The temperature dependence of the vortex penetration and expulsion fields in mesoscopic superconducting disks are studied. We experimentally find that the penetration field decreases with increasing temperature for all values of the vorticity. On the other hand, the temperature dependence of the expulsion fields shows two regimes: For some vortex states the expulsion field increases with temperature, while for other states it is almost temperature independent. A numerical study based on the nonlinear Ginzburg-Landau theory confirms that the former regime corresponds to multivortex states and the latter to giant vortex states. The origin of this difference is discussed.

著者

Kakeya I. Wada T. Nakamura R. Kadowaki K.

出版者

American Physical Society

雑誌

Physical review B (ISSN:10980121)

巻号頁・発行日

vol.72, pp.014540, 2005-07

被引用文献数

14 10

---

Josephson plasma excitations in the high-Tc superconductor Bi2Sr2CaCu2O8+delta have been investigated in a wide microwave frequency region (9.8–75 GHz)—in particular, in a magnetic field applied parallel to the ab plane of the single crystal. In sharp contrast to the case for magnetic fields parallel to the c axis or tilted from the ab plane, it was found that there are two kinds of resonance modes, which are split in energy and possess two distinctly different magnetic field dependences. One always lies higher in energy than the other and has a shallow minimum at about 0.8 kOe, then increases linearly with magnetic field. On the other hand, another mode begins to appear only in a magnetic field (from a few kOe and higher) and has a weakly decreasing tendency with increasing magnetic field. By comparing with a recent theoretical model the higher-energy mode can naturally be attributed to the Josephson plasma resonance mode propagating along the primitive reciprocal lattice vector of the Josephson vortex lattice, whereas the lower-frequency mode is assigned to the novel phase collective mode of the Josephson vortex lattice, which has never been observed before.

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 S. Fukugita M. Hashimoto S. Ishikawa K.-I. Ishizuka N. Iwasaki Y. Kanaya K. Kaneko T. Kuramashi Y. Okawa M. 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.69, no.9, pp.094512, 2004-05

被引用文献数

5

---

We present a lattice QCD calculation of the heavy quark expansion parameters µpi2 and µG2 for heavy-light mesons and heavy-light-light baryons. The calculation is carried out on a 203×48 lattice at beta=6.0 in the quenched approximation, using the lattice NRQCD action for heavy quarks. We obtain the parameters µpi2 and µG2 in two different methods: a direct calculation of the matrix elements and an indirect calculation through the mass spectrum, and confirm that both the methods give consistent results. We also discuss an application to the lifetime ratios.

著者

Iwasaki Y. Kanaya K. Kaya S. Sakai S. Yoshié T.

出版者

American Physical Society

雑誌

Physical review D (ISSN:05562821)

巻号頁・発行日

vol.69, pp.014507, 2004-01

被引用文献数

66

---

We investigate the phase structure of lattice QCD for the general number of flavors in the parameter space of gauge coupling constant and quark mass, employing the one-plaquette gauge action and the standard Wilson quark action. Performing a series of simulations for the number of flavors NF = 6–360 with degenerate-mass quarks, we find that when NF>=7 there is a line of a bulk first order phase transition between the confined phase and a deconfined phase at a finite current quark mass in the strong coupling region and the intermediate coupling region. The massless quark line exists only in the deconfined phase. Based on these numerical results in the strong coupling limit and in the intermediate coupling region, we propose the following phase structure, depending on the number of flavors whose masses are less than Lambdad which is the physical scale characterizing the phase transition in the weak coupling region: When NF>=17, there is only a trivial IR fixed point and therefore the theory in the continuum limit is free. On the other hand, when 16>=NF>=7, there is a nontrivial IR fixed point and therefore the theory is nontrivial with anomalous dimensions, however, without quark confinement. Theories which satisfy both quark confinement and spontaneous chiral symmetry breaking in the continuum limit exist only for NF<=6.

著者

Aoki S. Burkhalter R. 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 D (ISSN:05562821)

巻号頁・発行日

vol.68, no.5, pp.054502, 2003-09

被引用文献数

98 238

---

We present a high statistics study of the light hadron spectrum and quark masses in QCD with two flavors of dynamical quarks. Numerical simulations are carried out using the plaquette gauge action and the O(a)-improved Wilson quark action at β=5.2, where the lattice spacing is found to be a=0.0887(11) fm from the ρ meson mass, on a 203×48 lattice. At each of five sea quark masses corresponding to mPS/mV≃0.8–0.6, we generate 12 000 trajectories using a symmetrically preconditioned Hybrid Monte Carlo algorithm. Finite spatial volume effects are investigated employing 123×48, 163×48 lattices. We also perform a set of simulations in quenched QCD with the same lattice actions at a similar lattice spacing to those for the full QCD runs. In the meson sector we find clear evidence of sea quark effects. The J parameter increases for lighter sea quark masses, and the full QCD meson masses are systematically closer to experiment than in quenched QCD. Careful finite-size studies are made to ascertain that these are not due to finite-size effects. Evidence of sea quark effects is less clear in the baryon sector due to larger finite-size effects. We also calculate light quark masses and find mudMS̅ (2 GeV)=3.223(-0.069+0.046) MeV and msMS̅ (2 GeV)=84.5(-1.7+12.0) MeV which are about 20% smaller than in quenched QCD.