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111.
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 Lynch G Mir LM Orimoto TJ Pripstein M Roe NA Ronan MT Wenzel WA Sanchez Pdel A Barrett M Ford KE Hart AJ Harrison TJ Hawkes CM Watson AT Held T Koch H Lewandowski B Pelizaeus M Peters K 《Physical review letters》2006,97(26):261803
We report measurements of the decays B(+)-->phiphiK(+) and B(0)-->phiphiK(0) using a sample of 231 x 10(6) BB pairs collected with the BABAR detector at the PEP-II asymmetric-energy B factory at the Stanford Linear Accelerator Center. The branching fractions are measured to be B(B(+)-->phiphiK(+))=(7.5+/-1.0(stat)+/-0.7(syst)) x 10(-6) and B(B(0)-->phiphiK(0))=(4.1(-1.4)(+1.7)(stat)+/-0.4(syst)) x 10(-6) for a phiphi invariant mass below 2.85 GeV/c(2). 相似文献
112.
Streed EW Mun J Boyd M Campbell GK Medley P Ketterle W Pritchard DE 《Physical review letters》2006,97(26):260402
Continuous and pulsed quantum Zeno effects were observed using a 87Rb Bose-Einstein condensate. Oscillations between two ground hyperfine states of a magnetically trapped condensate, externally driven at a transition rate omega(R), were suppressed by destructively measuring the population in one of the states with resonant light. The suppression of the transition rate in the two-level system was quantified for pulsed measurements with a time interval deltat between pulses and continuous measurements with a scattering rate gamma. We observe that the continuous measurements exhibit the same suppression in the transition rate as the pulsed measurements when gammadeltat=3.60(0.43), in agreement with the predicted value of 4. Increasing the measurement rate suppressed the transition rate down to 0.005 omega(R). 相似文献
113.
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 Lynch G Mir LM Orimoto TJ Pripstein M Roe NA Ronan MT Wenzel WA del Amo Sanchez P Barrett M Ford KE Hart AJ Harrison TJ Hawkes CM Watson AT Held T Koch H Lewandowski B Pelizaeus M Peters K 《Physical review letters》2006,97(23):232001
We report the first observation of an excited singly charmed baryon Omega c* (css) in the radiative decay Omega c0gamma, where the Omega c0 baryon is reconstructed in the decays to the final states Omega(-)pi+, Omega(-)pi+pi0, Omega(-)pi+pi(-)pi+, and Xi(-)K(-)pi+pi+. This analysis is performed using a data set of 230.7 fb(-1) collected by the BABAR detector at the PEP-II asymmetric-energy B factory at the Stanford Linear Accelerator Center. The mass difference between the Omega c* and the Omega c0 baryons is measured to be 70.8+/-1.0(stat)+/-1.1(syst) MeV/c2. We also measure the ratio of inclusive production cross sections of Omega c* and Omega c0 in e+e(-) annihilation. 相似文献
114.
Aubert B Barate R 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 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 Morgan SE Watson AT Held T Koch H Lewandowski B 《Physical review letters》2006,97(21):211801
We report a measurement of the B-->pi l nu branching fraction based on 211 fb(-1) of data collected with the BABAR detector. We use samples of B0 and B+ mesons tagged by a second B meson reconstructed in a semileptonic or hadronic decay and combine the results assuming isospin symmetry to obtain B(B(0)-->pi- l+ nu) = (1.33+/-0.17stat+/-0.11syst) x 10(-4). We determine the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element absolute value V(ub) by combining the partial branching fractions measured in ranges of the momentum transfer squared and theoretical calculations of the form factor. Using a recent lattice QCD calculation, we find absolute value V(ub) = (4.5+/-0.5stat+/-0.3syst(+0.7) -0.5FF x 10(-3), where the last error is due to the normalization of the form factor. 相似文献
115.
Michael DG Adamson P Alexopoulos T Allison WW Alner GJ Anderson K Andreopoulos C Andrews M Andrews R Arms KE Armstrong R Arroyo C Auty DJ Avvakumov S Ayres DS Baller B Barish B Barker MA Barnes PD Barr G Barrett WL Beall E Becker BR Belias A Bergfeld T Bernstein RH Bhattacharya D Bishai M Blake A Bocean V Bock B Bock GJ Boehm J Boehnlein DJ Bogert D Border PM Bower C Boyd S Buckley-Geer E Bungau C Byon-Wagner A Cabrera A Chapman JD Chase TR Cherdack D Chernichenko SK Childress S Choudhary BC 《Physical review letters》2006,97(19):191801
This Letter reports results from the MINOS experiment based on its initial exposure to neutrinos from the Fermilab NuMI beam. The rates and energy spectra of charged current nu(mu) interactions are compared in two detectors located along the beam axis at distances of 1 and 735 km. With 1.27 x 10(20) 120 GeV protons incident on the NuMI target, 215 events with energies below 30 GeV are observed at the Far Detector, compared to an expectation of 336+/-14 events. The data are consistent with nu(mu) disappearance via oscillations with |Delta(m)2/32|=2.74 +0.44/-0.26 x10(-3)eV(2) and sin(2)(2theta(23))>0.87 (68% C.L.). 相似文献
116.
Aubert B Barate R 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 Lynch G Mir LM Oddone PJ Orimoto TJ Pripstein M Roe NA Ronan MT Wenzel WA del Amo Sanchez P Barrett M Ford KE Harrison TJ Hart AJ Hawkes CM Morgan SE Watson AT Goetzen K Held T Koch H 《Physical review letters》2006,97(17):171803
The photon spectrum in B-->Xs gamma decay, where Xs is any strange hadronic state, is studied using a data sample of 88.5 x 10(6) e+ e- --> Upsilon(4S) --> BB decays collected by the BABAR experiment at the Stanford Linear Accelerator Center. The partial branching fraction, DeltaB(B --> Xs gamma) = (3.67+/-0.29(stat)+/-0.34(syst)+/-0.29(model)) x 10(-4), the first moment = 2.288+/-0.025+/-0.017+/-0.015 GeV, and the second moment E2(gamma) = 0.0328+/-0.0040+/-0.0023+/-0.0036 GeV2 are measured for the photon energy range 1.9 GeV < E gamma < 2.7 GeV. They are also measured for narrower E gamma ranges. The moments are then fit to recent theoretical calculations to extract the heavy quark expansion parameters m(b) and mu2(pi) and to extrapolate the partial branching fraction to E gamma > 1.6 GeV. In addition, the direct CP asymmetry A(CP)(B-->X(s+d gamma) is measured to be -0.110+/-0.115(stat)+/-0.017(syst). 相似文献
117.
Campbell GK Mun J Boyd M Streed EW Ketterle W Pritchard DE 《Physical review letters》2006,96(2):020406
We have observed parametric generation and amplification of ultracold atom pairs. A 87Rb Bose-Einstein condensate was loaded into a one-dimensional optical lattice with quasimomentum k0 and spontaneously scattered into two final states with quasimomenta k1 and k2 . Furthermore, when a seed of atoms was first created with quasimomentum k1 we observed parametric amplification of scattered atoms pairs in states k1 and k2 when the phase-matching condition was fulfilled. This process is analogous to optical parametric generation and amplification of photons and could be used to efficiently create entangled pairs of atoms. Furthermore, these results explain the dynamic instability of condensates in moving lattices observed in recent experiments. 相似文献
118.
The range of available arene dihydroxylating dioxygenase enzymes, their structure and mechanism, and recent examples of the application of arene cis-dihydrodiol bioproducts as chiral precursors in the synthesis of natural and unnatural products and chiral ligands are discussed. 相似文献
119.
Boyd DR Sharma ND Bowers NI Dalton H Garrett MD Harrison JS Sheldrake GN 《Organic & biomolecular chemistry》2006,4(17):3343-3349
Biotransformations of a series of ortho-, meta- and para-substituted ethylbenzene and propylbenzene substrates have been carried out, using Pseudomonas putida UV4, a source of toluene dioxygenase (TDO). The ortho- and para-substituted alkylbenzene substrates yielded, exclusively, the corresponding enantiopure cis-dihydrodiols of the same absolute configuration. However, the meta isomers, generally, gave benzylic alcohol bioproducts, in addition to the cis-dihydrodiols (the meta effect). The benzylic alcohols were of identical (R) absolute configuration but enantiomeric excess values were variable. The similar (2R) absolute configurations of the cis-dihydrodiols are consistent with both the ethyl and propyl groups having dominant stereodirecting effects over the other substituents. The model used earlier, to predict the regio- and stereo-chemistry of cis-dihydrodiol bioproducts derived from substituted benzene substrates has been refined, to take account of non-symmetric substituents like ethyl or propyl groups. The formation of benzylic hydroxylation products, from meta-substituted benzene substrates, without further cis-dihydroxylation to yield triols provides a further example of the meta effect during toluene dioxygenase-catalysed oxidations. 相似文献
120.
Reaction of hexa-N-Boc neomycin B with TPP and DIAD in toluene results in the formation of an epoxide in ring IV, not an aziridine or azetidine as previously reported. 相似文献