343 research outputs found

    When I say … team reflexivity

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    First Measurement of Gamma(D*+) and Precision Measurement of m_D*+ - m_D0

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    We present the first measurement of the D*+ width using 9/fb of e+ e- data collected near the Upsilon(4S) resonance by the CLEO II.V detector. Our method uses advanced tracking techniques and a reconstruction method that takes advantage of the small vertical size of the CESR beam spot to measure the energy release distribution from the D*+ -> D0 pi+ decay. We find Gamma(D*+) = 96 +- 4 (Statistical) +- 22 (Systematic) keV. We also measure the energy release in the decay and compute Delta m = m(D*+) - m(D0) = 145.412 +- 0.002 (Statistical) +- 0.012 (Systematic) MeV/c^2Comment: 24 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, submitted to PR

    Rate Measurement of D0K+ππ0D^{0}\to K^{+}\pi^{-}\pi^{0} and Constraints on D0D0D^{0} - \overline{D^{0}} Mixing

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    We present an observation and rate measurement of the decay D0 -> K+pi-pi0 produced in 9/fb of e+e- collisions near the Upsilon(4S) resonance. The signal is inconsistent with an upward fluctuation of the background by 4.9 standard deviations. We measured the rate of D0 -> K+pi-pi0 normalized to the rate of D0bar -> K+pi-pi0 to be 0.0043 +0.0011 -0.0010 (stat) +/- 0.0007 (syst). This decay can be produced by doubly-Cabibbo-suppressed decays or by the D0 evolving into a D0bar through mixing, followed by a Cabibbo-favored decay to K+pi-pi0. We also found the CP asymmetry A=(8 +25 -22)% to be consistent with zero.Comment: 10 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

    Observation of Two Narrow States Decaying into Ξc+γ\Xi_{c}^{+}\gamma and Ξc0γ\Xi_{c}^{0}\gamma

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    We report the first observation of two narrow charmed strange baryons decaying to Ξc+γ\Xi_c^+\gamma and Ξc0γ\Xi_c^0\gamma, respectively, using data from the CLEO II detector at CESR. We interpret the observed signals as the Ξc+(csu)\Xi_c^{+\prime}(c{su}) and Ξc0(csd)\Xi_c^{0\prime}(c{sd}), the symmetric partners of the well-established antisymmetric Ξc+(c[su])\Xi_c^+(c[su]) and Ξc0(c[sd])\Xi_c^0(c[sd]). The mass differences M(Ξc+)M(Ξc+)M(\Xi_c^{+\prime})-M(\Xi_c^+) and M(Ξc0)M(Ξc0)M(\Xi_c^{0\prime})-M(\Xi_c^0) are measured to be 107.8±1.7±2.5107.8\pm 1.7\pm 2.5 and 107.0±1.4±2.5MeV/c2107.0\pm 1.4\pm 2.5 MeV/c^2, respectively.Comment: 11 pages, postscript file also available through http://w4.lns.cornell.edu/public/CLN

    Observation of the Dynamic Beta Effect at CESR with CLEO

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    Using the silicon strip detector of the CLEO experiment operating at the Cornell Electron-positron Storage Ring (CESR), we have observed that the horizontal size of the luminous region decreases in the presence of the beam-beam interaction from what is expected without the beam-beam interaction. The dependence on the bunch current agrees with the prediction of the dynamic beta effect. This is the first direct observation of the effect.Comment: 9 page uuencoded postscript file, postscritp file also available through http://w4.lns.cornell.edu/public/CLNS, submitted to Phys. Rev.

    Study of the Decays B0 --> D(*)+D(*)-

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    The decays B0 --> D*+D*-, B0 --> D*+D- and B0 --> D+D- are studied in 9.7 million Y(4S) --> BBbar decays accumulated with the CLEO detector. We determine Br(B0 --> D*+D*-) = (9.9+4.2-3.3+-1.2)e-4 and limit Br(B0 --> D*+D-) < 6.3e-4 and Br(B0 --> D+D-) < 9.4e-4 at 90% confidence level (CL). We also perform the first angular analysis of the B0 --> D*+D*- decay and determine that the CP-even fraction of the final state is greater than 0.11 at 90% CL. Future measurements of the time dependence of these decays may be useful for the investigation of CP violation in neutral B meson decays.Comment: 21 pages, 5 figures, submitted to Phys. Rev.

    Measurement of B(/\c->pKpi)

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    The /\c->pKpi yield has been measured in a sample of two-jet continuum events containing a both an anticharm tag (Dbar) as well as an antiproton (e+e- -> Dbar pbar X), with the antiproton in the hemisphere opposite the Dbar. Under the hypothesis that such selection criteria tag e+e- -> Dbar pbar (/\c) X events, the /\c->pkpi branching fraction can be determined by measuring the pkpi yield in the same hemisphere as the antiprotons in our Dbar pbar X sample. Combining our results from three independent types of anticharm tags, we obtain B(/\c->pKpi)=(5.0+/-0.5+/-1.2)

    Teamwork in Antarctica

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    This document regards the report of the research project "Team Adaptation during Antarctica Summer Campaigns", supported by the Portuguese Polar Program (PROPOLAR). It contains general findings about teamwork in Antarctica and recommendations for practice
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