[en] Using a sample of 3.3x10⁶ Υ(4S)→BB(bar sign) events collected with the CLEO II detector at the Cornell Electron Storage Ring (CESR), we measure B(B→ρlν), |V_ub|, and the partial rate (ΔΓ) in three bins of q²≡(p_B-p_ρ)². We find B(B⁰→ρ^-l⁺ν)=(2.69±0.41_-0.40^+0.35±0.50)x10^-4, |V_ub|=(3.23±0.24_-0.26^+0.23±0.58)x10^-3, ΔΓ(0< q²<7 GeV²/c⁴)=(7.6±3.0_-1.2^+0.9±3.0)x10^-2 ns^-1, ΔΓ(7< q²<14 GeV²/c⁴)=(4.8±2.9_-0.8^+0.7±0.7)x10^-2 ns^-1, and ΔΓ(14< q²<21 GeV²/c⁴)=(7.1±2.1_-1.1^+0.9±0.6)x10^-2 ns^-1. Here, l=e or μ, but not both, and the errors are statistical, systematic, and theoretical. The method is sensitive primarily to B→ρlν decays with leptons in the energy range above 2.3 GeV. Averaging with the previously published CLEO results for B→ρlν, we obtain B(B⁰→ρ^-l⁺ν)=(2.57±0.29_-0.46^+0.33±0.41)x10^-4 and |V_ub|=(3.25±0.14_-0.29^+0.21±0.55)x10^-3. (c) 2000 The American Physical Society

[en] We have searched for rare and forbidden decays of the η^' meson in hadronic events at the CLEO II detector. The search is conducted on 4.80 fb^-1 of e⁺e^- collisions at 10.6 GeV center-of-mass energy at the Cornell Electron Storage Ring. We find no signals, and set 90% confidence level upper limits of their branching fractions: B(η^'→e⁺e^- η)<2.4x10^-3 , B(η^'→e⁺e^- π⁰)<1.4x10^-3 , B(η^'→e⁺e^- γ)<0.9x10^-3 , and B(η^'→eμ)<4 .7x10^-4 . We also fit the matrix element of the η^'→π⁺π^-η Dalitz plot with the parametrization |M|²=A|1+αy|² , where y is a linear function of the kinetic energy of the η , and find Re(α)=-0.021±0.025 . (c) 1999 The American Physical Society

[en] A study of charm fragmentation into D_s^*+ and D_s⁺ in e⁺e^- annihilations at √(s)=10.5 GeV is presented. This study using 4.72±0.05 fb^-1 of CLEO II data reports measurements of the cross sections σ(D_s^*+) and σ(D_s⁺) in momentum regions above x=0.44, where x is the D_s momentum divided by the maximum kinematically allowed D_s momentum. The D_s vector to vector plus pseudoscalar production ratio is measured to be P_V(x(D_s⁺)>0.44)=0.44±0.04. (c) 2000 The American Physical Society

[en] Using a sample of 4.7 fb^-1 integrated luminosity accumulated with the CLEO II detector at the Cornell Electron Storage Ring (CESR), we investigate the mass spectrum and resonant structure in τ^-→K^-π⁺π^-ν_τ decays. We measure the relative fractions of K₁(1270) and K₁(1400) resonances in these decays, as well as the K₁ masses and widths. Our fitted K₁ resonances are somewhat broader than previous hadroproduction measurements, and in agreement with recent CERN LEP results from tau decay. The larger central value of our measured width supports models which attribute the small τ^-→K^-π⁺π^-ν_τ branching fraction to larger K₁ widths than are presently tabulated. We also determine the K_a-K_b mixing angle θ_K. (c) 2000 The American Physical Society