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81.
Study of the decay B0(B- 0)-->rho+rho-, and constraints on the Cabibbo-Kobayashi-Maskawa angle alpha
Aubert B Barate R Boutigny D Couderc F Gaillard JM Hicheur A Karyotakis Y Lees JP Tisserand V Zghiche A Palano A Pompili A Chen JC Qi ND Rong G Wang P Zhu YS Eigen G Ofte I Stugu B Abrams GS Borgland AW Breon AB Brown DN Button-Shafer J Cahn RN Charles E Day CT Gill MS Gritsan AV Groysman Y Jacobsen RG Kadel RW Kadyk J Kerth LT Kolomensky YG Kukartsev G LeClerc C Lynch G Merchant AM Mir LM Oddone PJ Orimoto TJ Pripstein M Roe NA Ronan MT Shelkov VG Wenzel WA Ford K Harrison TJ Hawkes CM 《Physical review letters》2004,93(23):231801
Using a data sample of 89 x 10(6) Upsilon(4S)-->BB decays collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC, we measure the B0(B (0))-->rho(+)rho(-) branching fraction as [30+/-4(stat)+/-5(syst)]x10(-6) and a longitudinal polarization fraction of f(L)=0.99+/-0.03(stat)+0.04-0.03(syst). We measure the time-dependent-asymmetry parameters of the longitudinally polarized component of this decay as C(L)=-0.17+/-0.27(stat)+/-0.14(syst) and S(L)=-0.42+/-0.42(stat)+/-0.14(syst). We exclude values of alpha between 19 degrees and 71 degrees (90% C.L.). 相似文献
82.
This paper describes the approach to bubble related phenomena using a novel 'acoustoelectrochemical' technique designed to investigate the physical and chemical effects of the acoustically induced motion of the bubble wall. In particular it describes the behaviour of a suspended gas bubble irradiated with sound of an appropriate frequency and pressure to induce bubble wall oscillation. The first electrochemical measurement of the growth of a bubble through rectified diffusion is demonstrated. The technique employed relies on the sensitivity of a scanning electrochemical microscope (SECM) deployed close to the gas/liquid interface of a bubble. The growth rate of the bubble (<0.1 microms(-1)) is reported. It will be also demonstrated that gas exchange across the phase boundary at the bubble wall, can be successfully probed when the bubble is stationary. 相似文献
83.
William H. Watson Guanmin Wu Michael G. Richmond 《Journal of chemical crystallography》2004,34(9):621-625
The reaction of p-toluidine with 2,3-dichloromaleic anhydride in the presence of added 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) does not give the known compound 2-chloro-3-p-toluidino-N-p-tolylmaleimide (1), but rather 2-p-toluidino-N-p-tolylmaleimide (2) in low yields. Repeating this same reaction with Et3N, pyridine, tmeda, and 4-Me2Npyridine in place of DBU furnishes the expected product 2-chloro-3-p-toluidino-N-p-tolylmaleimide, without the presence of 2-p-toluidino-N-p-tolylmaleimide. The participation of DBU in the chlorine for hydrogen exchange reaction in compound 1 has been demonstrated from the independent thermolysis reaction of 1 with DBU in toluene, where 2 was obtained as the sole isolable product. Compound 2 was isolated and fully characterized in solution, and the molecular structure was established by X-ray diffraction analysis. 2-p-Toluidino-N-p-tolylmaleimide crystallizes in the monoclinic space C2/c, a = 33.630(5), b = 12.508(2), c = 7.381(1), = 90.668(3), V = 3104.3(8)3, Z = 8, and D
calc = 1.251 Mg/m3; R = 0.0357, R
w = 0.0896 for 2011 reflections with I > 2(I). 相似文献
84.
William H. Watson Shih-Huang Huang Michael G. Richmond 《Journal of chemical crystallography》2004,34(9):565-569
Abstract List
Index abstracts 相似文献85.
Aubert B Barate R Boutigny D Couderc F Gaillard JM Hicheur A Karyotakis Y Lees JP Tisserand V Zghiche A Palano A Pompili A Chen JC Qi ND Rong G Wang P Zhu YS Eigen G Ofte I Stugu B Abrams GS Borgland AW Breon AB Brown DN Button-Shafer J Cahn RN Charles E Day CT Gill MS Gritsan AV Groysman Y Jacobsen RG Kadel RW Kadyk J Kerth LT Kolomensky YG Kukartsev G LeClerc C Lynch G Merchant AM Mir LM Oddone PJ Orimoto TJ Pripstein M Roe NA Ronan MT Shelkov VG Wenzel WA Ford K Harrison TJ Hawkes CM 《Physical review letters》2004,93(8):081802
We measure the branching fraction for the flavor-changing neutral-current process B-->X(s)l(+)l(-) with a sample of 89x10(6) Upsilon(4S)-->BBmacr; events recorded with the BABAR detector at the PEP-II e(+)e(-) storage ring. The final state is reconstructed from e(+)e(-) or micro(+)micro(-) pairs and a hadronic system X(s) consisting of one K+/- or K(0)(S) and up to two pions, with at most one pi(0). We observe a signal of 40+/-10(stat)+/-2(syst) events and extract the inclusive branching fraction B(B-->X(s)l(+)l(-))=(5.6+/-1.5(stat)+/-0.6(exp syst)+/-1.1(model syst))x10(-6) for ml(+)(l(-))>0.2 GeV/c(2). 相似文献
86.
Three experiments tested listeners' ability to identify 70 diverse environmental sounds using limited spectral information. Experiment 1 employed low- and high-pass filtered sounds with filter cutoffs ranging from 300 to 8000 Hz. Listeners were quite good (>50% correct) at identifying the sounds even when severely filtered; for the high-pass filters, performance was never below 70%. Experiment 2 used octave-wide bandpass filtered sounds with center frequencies from 212 to 6788 Hz and found that performance with the higher bandpass filters was from 70%-80% correct, whereas with the lower filters listeners achieved 30%-50% correct. To examine the contribution of temporal factors, in experiment 3 vocoder methods were used to create event-modulated noises (EMN) which had extremely limited spectral information. About half of the 70 EMN were identifiable on the basis of the temporal patterning. Multiple regression analysis suggested that some acoustic features listeners may use to identify EMN include envelope shape, periodicity, and the consistency of temporal changes across frequency channels. Identification performance with high- and low-pass filtered environmental sounds varied in a manner similar to that of speech sounds, except that there seemed to be somewhat more information in the higher frequencies for the environmental sounds used in this experiment. 相似文献
87.
Aubert B Barate R Boutigny D Gaillard JM Hicheur A Karyotakis Y Lees JP Robbe P Tisserand V Zghiche A Palano A Pompili A Chen JC Qi ND Rong G Wang P Zhu YS Eigen G Ofte I Stugu B Abrams GS Borgland AW Breon AB Brown DN Button-Shafer J Cahn RN Charles E Day CT Gill MS Gritsan AV Groysman Y Jacobsen RG Kadel RW Kadyk J Kerth LT Kolomensky YG Kral JF Kukartsev G LeClerc C Levi ME Lynch G Mir LM Oddone PJ Orimoto TJ Pripstein M Roe NA Romosan A Ronan MT Shelkov VG Telnov AV Wenzel WA Ford K 《Physical review letters》2004,92(7):071802
We report a measurement of the inclusive charmless semileptonic branching fraction of B mesons in a sample of 89 x 10(6) (-)BB events recorded with the BABAR detector at the Upsilon(4S) resonance. Events are selected by fully reconstructing the decay of one B meson and identifying a charged lepton from the decay of the other B meson. The number of signal events is extracted from the mass distribution of the hadronic system accompanying the lepton and is used to determine the ratio of branching fractions B((-)B-->X(u)lnu;)/B((-)B-->Xlnu;)=[2.06+/-0.25(stat)+/-0.23(syst)+/-0.36(theo)]x10(-2). Using the measured branching fraction for inclusive semileptonic B decays, we find B((-)B-->X(u)lnu;)=[2.24+/-0.27(stat)+/-0.26(syst)+/-0.39(theo)]x10(-3) and derive the Cabibbo-Kobayashi-Maskawa matrix element |V(ub)|=[4.62+/-0.28(stat)+/-0.27(syst)+/-0.48(theo)]x10(-3). 相似文献
88.
We demonstrate the operation of a quantum spin pump based on cyclic radio-frequency excitation of a GaAs quantum dot, including the ability to pump pure spin without pumping charge. The device takes advantage of bidirectional mesoscopic fluctuations of pumped current, made spin dependent by the application of an in-plane Zeeman field. Spin currents are measured by placing the pump in a focusing geometry with a spin-selective collector. 相似文献
89.
Watson PJ Ciccia AH Weismer G 《The Journal of the Acoustical Society of America》2003,113(5):2812-2819
This study examined the relationship of speech breathing to other elements of speech production. It was hypothesized that initiating speech from different lung volumes would have an effect on different elements of the acoustic output. It was postulated that effects may be brought about by mechanical interaction as well as a dispersion of effort to mechanically unlinked elements of speech production, such as articulatory behavior. To this end, selected acoustic variables were studied in eight young healthy women who initiated speech from low, typical, and high lung volume levels. The acoustic variables studied were selected because they have been shown to be sensitive indicators of speech production performance. It was found that with increasing lung volume initiation levels, average sound pressure level, average fundamental frequency, and declination rate of fundamental frequency increased. It was also observed that vowel space was significantly smaller during low lung volume initiation levels relative to typical lung volume initiation levels. Vowel space reduction is discussed relative to "gaining down." 相似文献
90.
Aubert B Barate R Boutigny D Gaillard JM Hicheur A Karyotakis Y Lees JP Robbe P Tisserand V Zghiche A Palano A Pompili A Chen JC Qi ND Rong G Wang P Zhu YS Eigen G Ofte I Stugu B Abrams GS Borgland AW Breon AB Brown DN Button-Shafer J Cahn RN Charles E Day CT Gill MS Gritsan AV Groysman Y Jacobsen RG Kadel RW Kadyk J Kerth LT Kolomensky YG Kral JF Kukartsev G LeClerc C Levi ME Lynch G Mir LM Oddone PJ Orimoto TJ Pripstein M Roe NA Romosan A Ronan MT Shelkov VG Telnov AV Wenzel WA Ford K 《Physical review letters》2003,91(22):221802
We present evidence for the flavor-changing neutral current decay B-->K*l+l- and a measurement of the branching fraction for the related process B-->K l+l-, where l+l- is either an epsilon+epsilon- or a mu+mu- pair. These decays are highly suppressed in the standard model, and they are sensitive to contributions from new particles in the intermediate state. The data sample comprises 123 x 10(6) Upsilon(4S)-->B(-)B decays collected with the BABAR detector at the SLAC PEP-II epsilon+epsilon- storage ring. Averaging over K(*) isospin and lepton flavor, we obtain the branching fractions B(B-->Kl+l-)=(0.65(+0.14)(-0.13)+/-0.04)x10(-6) and B(B-->K*l+l-)=(0.88(+0.33)(-0.29)+/-0.10)x10(-6), where the uncertainties are statistical and systematic, respectively. The significance of the B-->Kl+l- signal is over 8sigma, while for B-->K*l+l- it is 3.3sigma. 相似文献