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951.
Aubert B Bona M Karyotakis Y Lees JP Poireau V Prencipe E Prudent X Tisserand V Garra Tico J Grauges E Lopez L Palano A Pappagallo M Eigen G Stugu B Sun L Abrams GS Battaglia M Brown DN Cahn RN Jacobsen RG Kerth LT Kolomensky YG Lynch G Osipenkov IL Ronan MT Tackmann K Tanabe T Hawkes CM Soni N Watson AT Koch H Schroeder T Walker D Asgeirsson DJ Fulsom BG Hearty C Mattison TS McKenna JA Barrett M Khan A Blinov VE Bukin AD Buzykaev AR Druzhinin VP Golubev VB Onuchin AP Serednyakov SI Skovpen YI 《Physical review letters》2008,101(7):071801
We report the results of a search for the bottomonium ground state etab(1S) in the photon energy spectrum with a sample of (109+/-1) million of Upsilon(3S) recorded at the Upsilon(3S) energy with the BABAR detector at the PEP-II B factory at SLAC. We observe a peak in the photon energy spectrum at Egamma=921.2(-2.8)+2.1(stat)+/-2.4(syst) MeV with a significance of 10 standard deviations. We interpret the observed peak as being due to monochromatic photons from the radiative transition Upsilon(3S)-->gammaetab(1S). This photon energy corresponds to an etab(1S) mass of 9388.9(-2.3)+3.1(stat)+/-2.7(syst) MeV/c2. The hyperfine Upsilon(1S)-etab(1S) mass splitting is 71.4(-3.1)+2.3(stat)+/-2.7(syst) MeV/c2. The branching fraction for this radiative Upsilon(3S) decay is estimated to be [4.8+/-0.5(stat)+/-1.2(syst)]x10(-4). 相似文献
952.
Aubert B Bona M Boutigny D Couderc F Karyotakis Y Lees JP Poireau V Tisserand V Zghiche A Grauges E Palano A Chen JC Qi ND Rong G Wang P Zhu YS Eigen G Ofte I Stugu B Abrams GS Battaglia M Brown DN Button-Shafer J Cahn RN Charles E Gill MS Groysman Y Jacobsen RG Kadyk JA Kerth LT Kolomensky YG Kukartsev G Pegna DL Lynch G Mir LM Orimoto TJ Pripstein M Roe NA Ronan MT Wenzel WA del Amo Sanchez P Barrett M Ford KE Harrison TJ Hart AJ Hawkes CM Watson AT Held T Koch H Lewandowski B Pelizaeus M 《Physical review letters》2008,100(1):011801
Using a data sample corresponding to an integrated luminosity of 342 fb(-1) collected with the BABAR detector at the SLAC PEP-II electron-positron storage ring operating at a center-of-mass energy near 10.58 GeV, we measure B(tau(-)--> pi(-)pi(-)pi+nu(tau)(ex.K(S0))=(8.83+/-0.01+/-0.13)%, B(tau(-) -->K(-)pi(-)pi+nu tau(ex.K(S0))=(0.273+/-0.002+/-0.009)%, B(tau(-) -->K(-)pi(-)K+nu tau)=(0.1346+/-0.0010+/-0.0036)%, and B(tau(-) -->K(-)K(-)K+nu tau)=(1.58+/-0.13+/-0.12)x10;{-5}, where the uncertainties are statistical and systematic, respectively. These include significant improvements over previous measurements and a first measurement of B(tau(-) -->K(-)K(-)K+nu tau) in which no resonance structure is assumed. We also report a first measurement of B(tau(-) -->var phi(-)nu tau)=(3.42+/-0.55+/-0.25)x10(-5), a new measurement of B(tau(-) -->var phi K(-)nu tau)=(3.39+/-0.20+/-0.28)x10(-5) and a first upper limit on B(tau(-) -->K(-)K(-)K+nu tau(ex.var phi)). 相似文献
953.
Sharma M Babcock E Andersen KH Barrón-Palos L Becker M Boag S Chen WC Chupp TE Danagoulian A Gentile TR Klein A Penttila S Petoukhov A Soldner T Tardiff ER Walker TG Wilburn WS 《Physical review letters》2008,101(8):083002
We have observed depolarization effects when high intensity cold neutron beams are incident on alkali-metal spin-exchange-polarized 3He cells used as neutron spin filters. This was first observed as a reduction of the maximum attainable 3He polarization and was attributed to a decrease of alkali-metal polarization, which led us to directly measure alkali-metal polarization and spin relaxation over a range of neutron fluxes at Los Alamos Neutron Science Center and Institute Laue-Langevin. The data reveal a new alkali-metal spin-relaxation mechanism that approximately scales as sqrt[phi_{n}], where phi_{n} is the neutron capture-flux density incident on the cell. This is consistent with an effect proportional to the concentration of electron-ion pairs but is much larger than expected from earlier work. 相似文献
954.
Aubert B Bona M Boutigny D Karyotakis Y Lees JP Poireau V Prudent X Tisserand V Zghiche A Garra Tico J Grauges E Lopez L Palano A Pappagallo M Eigen G Stugu B Sun L Abrams GS Battaglia M Brown DN Button-Shafer J Cahn RN Groysman Y Jacobsen RG Kadyk JA Kerth LT Kolomensky YG Kukartsev G Lopes Pegna D Lynch G Mir LM Orimoto TJ Osipenkov IL Ronan MT Tackmann K Tanabe T Wenzel WA Del Amo Sanchez P Hawkes CM Watson AT Held T Koch H Pelizaeus M Schroeder T Steinke M Walker D Asgeirsson DJ 《Physical review letters》2008,101(8):082001
We present a study of the decays B;{0,+}-->J/psiomegaK;{0,+} using 383x10;{6} BB[over ] events obtained with the BABAR detector at PEP-II. We observe Y(3940)-->J/psiomega, with mass 3914.6_{-3.4};{+3.8}(stat)+/-2.0(syst) MeV/c;{2}, and width 34_{-8};{+12}(stat)+/-5(syst) MeV. The ratio of B0 and B+ decay to YK is 0.27_{-0.23};{+0.28}(stat)-0.01+0.04(syst), and the relevant B0 and B+ branching fractions are reported. 相似文献
955.
Aubert B Bona M Boutigny D Karyotakis Y Lees JP Poireau V Prudent X Tisserand V Zghiche A Garra Tico J Grauges E Lopez L Palano A Pappagallo M Eigen G Stugu B Sun L Abrams GS Battaglia M Brown DN Button-Shafer J Cahn RN Groysman Y Jacobsen RG Kadyk JA Kerth LT Kolomensky YG Kukartsev G Lopes Pegna D Lynch G Mir LM Orimoto TJ Osipenkov IL Ronan MT Tackmann K Tanabe T Wenzel WA Del Amo Sanchez P Hawkes CM Watson AT Koch H Schroeder T Walker D Asgeirsson DJ Cuhadar-Donszelmann T Fulsom BG Hearty C 《Physical review letters》2008,100(13):131802
We report results of a search for CPT and Lorentz violation in B(0)-B[over ](0) oscillations using inclusive dilepton events from 232 x 10(6) Upsilon(4S)-->BB[over ] decays recorded by the BABAR detector at the PEP-II B Factory at SLAC. We find 2.8sigma significance, compatible with no signal, for variations in the complex CPT violation parameter z at the Earth's sidereal frequency and extract values for the quantities Deltaa(micro) in the general Lorentz-violating standard-model extension. The spectral powers for variations in z over the frequency range 0.26 yr(-1) to 2.1 solar day(-1) are also compatible with no signal. 相似文献
956.
S.David Chappell David J. Cole-Hamilton Anita M.R. Galas Michael B. Hursthouse Nigel P.C. Walker 《Polyhedron》1985,4(1):121-125
Reaction of [RhCl(PPh3)3] with [o-MeC6H4CH2MgBr] affords high yields of the non-fluxional complex, [Rh(CH2C6H4Me)(PPh3)2] which has been shown crystallographically to contain a 1-3-η-benzyl group bound through the phenyl carbon atom that is not substituted with the methyl group. Crystals of this compound are triclinic, space group P, with a = 10.561(6). b = 17.705(3), c = 10.934(4) Å, α = 80.69(3), β = 116.86(4), γ = 102.30(4)° and Z = 2. The structure was solved via the heavy-atom method and refined to R = 0.032 using 5379 diffractometer data with I > 1.56(I). Attempts to prepare π-bonded xylylene complexes from this compound by reaction with base have been unsuccessful, but protonation followed by recrystallisation from acetone gives [Rh{(CH3)2CO}2(PPh3)2]BF4. 相似文献
957.
On Backtracking Failure in Newton–GMRES Methods with a Demonstration for the Navier–Stokes Equations
Raymond S. Tuminaro Homer F. Walker John N. Shadid 《Journal of computational physics》2002,180(2):549
In an earlier study of inexact Newton methods, we pointed out that certain counterintuitive behavior may occur when applying residual backtracking to the Navier–Stokes equations with heat and mass transport. Specifically, it was observed that a Newton–GMRES method globalized by backtracking (linesearch, damping) may be less robust when high accuracy is required of each linear solve in the Newton sequence than when less accuracy is required. In this brief discussion, we offer a possible explanation for this phenomenon, together with an illustrative numerical experiment involving the Navier–Stokes equations. 相似文献
958.
959.
The thermoreflectance spectrum of CuI in the 4–7 eV region is reported. New structure in the region has been assigned to the spin-orbit split triplet between the first valence band and the second conduction band at k=0. The magnitude of the splitting indicates an inverted order in the second conduction band and a large d-state mixture in the valence band. 相似文献
960.
Using a separable fixed scatterer pion-nucleon interaction and the distorted wave impulse approximation we have made predictions for medium energy pion inelastic scattering from 16O and (π?, π0) charge exchange from 48Ca. An optical potential based on the pion-nucleon interaction adopted in this work has been shown previously to provide good fits to pion-nucleus elastic scattering. After a discussion of the basic formulae, we present results of calculations for pion inelastic scattering from 16O for initial pion lab kinetic energies of 70 and 180 MeV. Because of the strong energy dependence of the pion-nucleon interaction there are qualitative differences between the predictions for the nuclear response in the momentum transfer, energy loss plane for Tπlab = 70 and 180 MeV. At these energies, states not prominently excited by other probes are predicted to be observable. In particular, Jπ = 3? and 4?, T = 0 states appear prominently in the excitation spectrum region at large momentum transfer. A comparison of π? and π+ scattering showing the effects of the Coulomb interaction is presented. The predictions for pion single-charge exchange on 48Ca indicate that this interaction would be useful for studying the location of the T> states arising from the splitting of the giant dipole resonance in T ≠ 0 nuclei. 相似文献