145 research outputs found

    Measurement of Exclusive B Decays to Final States Containing a Charmed Baryon

    Get PDF
    Using data collected by the CLEO detector in the Upsilon(4S) region, we report new measurements of the exclusive decays of B mesons into final states of the type Lambda_c^+ p-bar n(pi), where n=0,1,2,3. We find signals in modes with one, two and three pions and an upper limit for the two body decay Lambda_c^+ pbar. We also make the first measurements of exclusive decays of B mesons to Sigma_c p-bar n(pi), where n=0,1,2. We find signals in modes with one and two pions and an upper limit for the two body decay Sigma_c p-bar. Measurements of these modes shed light on the mechanisms involved in B decays to baryons.Comment: 11 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, submitted to PR

    Measurement of the Masses and Widths of the Sigma_c^++ and Sigma_c^0 Charmed Baryons

    Full text link
    Using data recorded by the CLEO II and CLEO II.V detector configurations at CESR, we report new measurements of the masses of the Sigma_c^{++} and Sigma_c^0 charmed baryons, and the first measurements of their intrinsic widths. We find M(Sigma_c^{++}) - M(Lambda_c^+) = 167.4 +- 0.1 +- 0.2 MeV, Gamma(Sigma_c^{++}) = 2.3 +- 0.2 +- 0.3 MeV, and M(Sigma_c^0) - M(Lambda_c^+) = 167.2 +- 0.1 +- 0.2 MeV, Gamma(Sigma_c^0) = 2.5 +- 0.2 +- 0.3 MeV, where the uncertainties are statistical and systematic, respectively.Comment: 9 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, submitted to PRD, Rapid Communications. Reference [13] correcte

    Evidence for the Decay D0→K+π−π+π−D^0\to K^+ \pi^-\pi^+\pi^-

    Full text link
    We present a search for the ``wrong-sign'' decay D0 -> K+ pi- pi+ pi- using 9 fb-1 of e+e- collisions on and just below the Upsilon(4S) resonance. This decay can occur either through a doubly Cabibbo-suppressed process or through mixing to a D0bar followed by a Cabibbo-favored process. Our result for the time-integrated wrong-sign rate relative to the decay D0 -> K- pi+ pi- pi+ is (0.0041 +0.0012-0.0011(stat.) +-0.0004(syst.))x(1.07 +-0.10)(phase space), which has a statistical significance of 3.9 standard deviations.Comment: 9 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, submitted to PR

    Observation of Exclusive barB --> D(*) K*- Decays

    Full text link
    We report the first observation of the exclusive decays \bar B\to D^{(*)}K^{*-}, using 9.66 x 10^{6} B\bar{B} pairs collected at the \Upsilon(4S) with the CLEO detector. We measure the following branching fractions: {\cal B}(B^- -> D^0 K^{*-})=(6.1 +- 1.6 +-1.7)x10^{-4}, {\cal B}(\bar{B^0} -> D^+K^{*-})=(3.7 +- 1.5 +- 1.0) x 10^{-4}, {\cal B}(\bar{B^0} -> D^{*+}K^{*-})=(3.8 +- 1.3 +- 0.8) x 10^{-4} and {\cal B}(B^- --> D^{*0} K^{*-})=(7.7 +- 2.2 +- 2.6) x 10^{-4}. The \bar B ->D^*K^{*-} branching ratios are the averages of those corresponding to the 00 and 11 helicity states. The errors shown are statistical and systematic, respectively.Comment: 9 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, Published in Phys.Rev.Lett.88:101803,200

    Search for the Decay ΄(1S)→γηâ€Č\Upsilon(1S)\to \gamma\eta^{'}

    Full text link
    We report on a search for the radiative decay U(1S) -> gamma + eta' in 61.3 pb^-1 of data taken with the CLEO II detector at the Cornell Electron Storage Ring. Three decay chains were investigated, all involving eta' -> pi+ pi- + eta, followed by eta -> gamma + gamma, eta -> pi0 + pi0 + pi0, or eta -> pi+ + pi- + pi0. We find no candidate events in any of the three cases and set a combined upper limit of 1.6 x 10^-5 at 90% C.L., significantly smaller than the previous limit. We compare our result to other radiative U(1S) decays, to radiative J/psi decays, and to theoretical predictions.Comment: 9 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, submitted to PR

    Cultural distance, mindfulness and passive xenophobia: Using Integrated Threat Theory to explore home higher education students' perspectives on 'internationalisation at home'

    Get PDF
    This paper addresses the question of interaction between home and international students using qualitative data from 100 home students at two 'teaching intensive' universities in the southwest of England. Stephan and Stephan's Integrated Threat Theory is used to analyse the data, finding evidence for all four types of threat that they predict when outgroups interact. It is found that home students perceive threats to their academic success and group identity from the presence of international students on the campus and in the classroom. These are linked to anxieties around 'mindful' forms of interaction and a taboo around the discussion of difference, leading to a 'passive xenophobia' for the majority. The paper concludes that Integrated Threat Theory is a useful tool in critiquing the 'internationalisation at home' agenda, making suggestions for policies and practices that may alleviate perceived threats, thereby improving the quality and outcomes of intercultural interaction. © 2010 British Educational Research Association

    Measurement of Gamma(ee)(J/psi), Gamma(tot)(J/psi), and Gamma(ee)[psi(2S)]/Gamma(ee)(J/psi)

    Get PDF
    Using data acquired with the CLEO detector at the CESR e(+)e(-) collider at root s=3.773 GeV, we measure the cross section for the radiative return process e(+)e(-)-\u3egamma J/psi, J/psi -\u3emu(+)mu(-), resulting in B(J/psi -\u3emu(+)mu(-))x Gamma(ee)(J/psi)=0.3384 +/- 0.0058 +/- 0.0071 keV, Gamma(ee)(J/psi)=5.68 +/- 0.11 +/- 0.13 keV, and Gamma(tot)(J/psi)=95.5 +/- 2.4 +/- 2.4 keV, in which the errors are statistical and systematic, respectively. We also determine the ratio Gamma(ee)[psi(2S)]/Gamma(ee)(J/psi)=0.45 +/- 0.01 +/- 0.02

    Measurement of the D+ --> K*0bar l+ nu_l Branching Fraction

    Full text link
    Using 13.53/fb of CLEO data, we have measured the ratios of the branching fractions R+(e) = BF(D+ --> K*0bar e+ nu_e) / BF(D+ --> K- pi+ pi+), R+(mu) = BF(D+ --> K*0bar mu+ nu_mu) / BF(D+ --> K- pi+ pi+) and the combined branching fraction ratio R+(l) = BF(D+ --> K*0bar l+ nu_l) / BF(D+ --> K- pi+ pi+). We find R+(e) = 0.74 +- 0.04 +- 0.05, R+(mu) = 0.72 +- 0.10 +- 0.06 and R+(l) = 0.74 +- 0.04 +- 0.05, where the first and second errors are statistical and systematic respectively. The known branching fraction BF(D+ --> K- pi+ pi+) leads to: BF(D+ --> K*0bar e+ nu_e) = (6.7 +- 0.4 +- 0.5 +- 0.4)%, BF(D+ --> K*0bar mu+ \nu_mu) = (6.5 +- 0.9 +- 0.5 +- 0.4)% and BF(D+ --> K*0bar l+ nu_l) = (6.7 +- 0.4 +- 0.5 +- 0.4)%, where the third error is due to the uncertainty in BF(D+ --> K- pi+ pi+).Comment: 10 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, Submitted to PR

    Photon transitions in psi(2S) decays to chi(cJ)(1P) and eta(c)(1S)

    Get PDF
    We have studied the inclusive photon spectrum in psi(2S) decays using the CLEO III detector. We present the most precise measurements of electric dipole (E1) photon transition rates for psi(2S)--\u3egammachi(cJ)(1P) (J=0,1,2). We also confirm the hindered magnetic dipole (M1) transition, psi(2S)--\u3egammaeta(c)(1S). However, the direct M1 transition psi(2S)--\u3egammaeta(c)(2S) observed by the Crystal Ball as a narrow peak at a photon energy of 91 MeV is not found in our data
    • 

    corecore