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971.
Aoki S Fukugita M Hashimoto S Ishikawa KI Ishizuka N Iwasaki Y Kanaya K Kaneko T Kuramashi Y Okawa M Onogi T Tsutsui N Ukawa A Yamada N Yoshié T;JLQCD Collaboration 《Physical review letters》2003,91(21):212001
We present an unquenched lattice calculation for the B(0)-B(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 f(B(d))=191(10)(+12-22) MeV, f(B(s))/f(B(d))=1.13(3)(+13-2), B(B(d))(m(b))=0.836(27)(+56-62), B(B(s))/B(B(d))=1.017(16)(+56-17), and xi=1.14(3)(+13-2), 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. 相似文献
972.
Malek M Morii M Fukuda S Fukuda Y Ishitsuka M Itow Y Kajita T Kameda J Kaneyuki K Kobayashi K Koshio Y Miura M Moriyama S Nakahata M Nakayama S Namba T Okada A Ooyabu T Saji C Sakurai N Shiozawa M Suzuki Y Takeuchi H Takeuchi Y Totsuka Y Yamada S Desai S Earl M Kearns E Messier MD Stone JL Sulak LR Walter CW Goldhaber M Barszczak T Casper D Gajewski W Kropp WR Mine S Liu DW Smy MB Sobel HW Vagins MR Gago A Ganezer KS Keig WE Ellsworth RW Tasaka S Kibayashi A Learned JG Matsuno S Takemori D 《Physical review letters》2003,90(6):061101
A search for the relic neutrinos from all past core-collapse supernovae was conducted using 1496 days of data from the Super-Kamiokande detector. This analysis looked for electron-type antineutrinos that had produced a positron with an energy greater than 18 MeV. In the absence of a signal, 90% C.L. upper limits on the total flux were set for several theoretical models; these limits ranged from 20 to 130 macro nu(e) cm(-2) s(-1). Additionally, an upper bound of 1.2 macro nu(e) cm(-2) s(-1) was set for the supernova relic neutrino flux in the energy region E(nu)>19.3 MeV. 相似文献
973.
Yamada TK Bischoff MM Heijnen GM Mizoguchi T Van Kempen H 《Physical review letters》2003,90(5):056803
We report the observation of a magnetic contrast of up to 20% in the scanning tunneling spectroscopy dI/dV maps obtained with Fe-coated tips on Mn(001) layers grown on an Fe(001) whisker at 370 K. These nanometer resolution microscopy results show that the layers couple antiferromagnetically. By normalizing the dI/dV curves by tunneling probability functions, we found a spin-dependent peak on the body-centered-tetragonal (bct) Mn(001) surface at +0.8 V, whose high spin polarization gives rise to the dI/dV map contrast. Band structure calculations allow one to identify the +0.8 V peak as due to two spin-polarized d(z(2)) surface states. 相似文献
974.
Wavelength division with three-dimensional couplers fabricated by filamentation of femtosecond laser pulses 总被引:1,自引:0,他引:1
Refractive-index changes can be induced by filamentation of 800-nm, 1-kHz femtosecond laser pulses in silica glass. Two-dimensional translation of a 40-microm-long filament leads to the formation of a curved waveguide because of bending by the previously induced refractive-index change. The fabrication of 2-mm directional couplers to split the coupled beam into 1:1 at a wavelength of 632.8 nm is demonstrated. The realization of three-dimensional directional couplers and wavelength division in the output from the couplers is also demonstrated. 相似文献
975.
Y. Kojima M. Shibata A. Taniguchi T. Hanafusa E. Yoshida K. Shizuma Y. Kawase S. Yamada 《The European Physical Journal A - Hadrons and Nuclei》2003,16(3):331-336
The β--decay of 151Pr produced by the thermal neutron-induced fission of 235U has been studied using an on-line isotope separator. From an internal-conversion electron measurement with a Si(Li) detector,
K-conversion coefficients were obtained for 20 γ-transitions. Spins and parities of 6 excited levels in 151Nd were newly determined from the deduced multipolarities: even parities for the 543 and 627 keV levels, odd parities for
250 and 599 keV, (3/2, 5/2)+ for 685 keV, and (1/2, 3/2)+ for 880 keV. The level structure was compared with the rotation-vibration coupling Nilsson model.
Received: 28 June 2002 / Accepted: 31 October 2002 / Published online: 25 February 2003
RID="a"
ID="a"e-mail: ykojima@hiroshima-u.ac.jp
Communicated by J. ?yst? 相似文献
976.
Yamada K Kurokawa T Tokuyama H Fukuyama T 《Journal of the American Chemical Society》2003,125(22):6630-6631
The total synthesis of (+)-duocarmycin A and SA through a common indoline intermediate is described. The key reactions include selective lithiation of a 2,6-dibromoiodobenzene derivative and diastereoselective addition to a chiral nitroalkene, copper-mediated aryl amination, and addition of aryllithium to azlactones. 相似文献
977.
Fukami T Yamaguchi K Tozuka Y Moribe K Oguchi T Yamamoto K 《Chemical & pharmaceutical bulletin》2003,51(2):227-229
The crystal structure of inclusion complex between ursodeoxycholic acid (UDCA), and phenanthrene has been determined. UDCA molecules formed hydrogen bond network to provide the channel structure along b axis, and phenanthrene molecules were accommodated in the cavity with a stoichiometry of 1 : 1 molar ratio. The channel structure observed in the UDCA-phenanthrene complex was significantly different from that of inclusion complex previously reported for deoxycholic acid (DCA) and cholic acid (CA). Because of the mesh-like hydrogen bond network, channel framework of UDCA could have less flexibility than that of DCA and CA. The difference of molecular state of phenanthrene was clearly observed in solid-state fluorescence measurement. 相似文献
978.
Yamada K Nomura Y Citterio D Iwasawa N Suzuki K 《Journal of the American Chemical Society》2005,127(19):6956-6957
A non-PET and non-PCT fluoroionophore has been designed and synthesized based on the combination of a biaryl boron-dipyrromethene fluorophore with an oligoethyleneglycol bridge. A specific red-shift response of absorption for NaClO4 in acetonitrile was demonstrated based on conformational restriction triggered by cation recognition at the bridge. The concentration of Na+ can be determined accurately using fluorescence due to a high extinction coefficient (epsilon = 50 000), a high fluorescence quantum yield (Phif = 0.68), and the sharpness of absorption and emission peaks of the boron-dipyrromethene derivative. 相似文献
979.
Inelastically tunneled electrons from a scanning tunneling microscope (STM) were used to induce vibrationally mediated motion of a single cis-2-butene molecule among four equivalent orientations on Pd(110) at 4.8 K. The action spectrum obtained from the motion clearly detects more vibrational modes than inelastic electron tunneling spectroscopy with a STM. We demonstrate the usefulness of the action spectroscopy as a novel single molecule vibrational spectroscopic method. We also discuss its selection rules in terms of resonance tunneling. 相似文献
980.
Matsui H Terashima K Sato T Takahashi T Wang SC Yang HB Ding H Uefuji T Yamada K 《Physical review letters》2005,94(4):047005
We performed high-resolution angle-resolved photoemission spectroscopy on Nd1.87Ce0.13CuO4, which is located at the boundary of the antiferromagnetic (AF) and the superconducting phase. We observed that the quasiparticle (QP) effective mass around (pi,0) is strongly enhanced due to the opening of the AF gap. The QP mass and the AF gap are found to be anisotropic, with the largest value near the intersecting point of the Fermi surface and the AF zone boundary. In addition, we observed that the QP peak disappears around the Néel temperature (TN) while the AF pseudogap is gradually filled up at much higher temperatures, possibly due to the short-range AF correlation. 相似文献