Measurement of the Relative Branching Fraction of Υ(4S)\Upsilon(4S) to Charged and Neutral B-Meson Pairs

We analyze 9.7 x 10^6 B\bar{B}$ pairs recorded with the CLEO detector to determine the production ratio of charged to neutral B-meson pairs produced at the Y(4S) resonance. We measure the rates for B^0 -> J/psi K^{(*)0} and B^+ -> J/psi K^{(*)+} decays and use the world-average B-meson lifetime ratio to extract the relative widths f+-/f00 = Gamma(Y(4S) -> B+B-)/Gamma(Y(4S) -> B0\bar{B0}) = = 1.04 +/- 0.07(stat) +/- 0.04(syst). With the assumption that f+- + f00 = 1, we obtain f00 = 0.49 +/- 0.02(stat) +/- 0.01(syst) and f+- = 0.51 +/- 0.02(stat) +/- 0.01(syst). This production ratio and its uncertainty apply to all exclusive B-meson branching fractions measured at the Y(4S) resonance.Comment: 11 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

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

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.

A Search for B→τνB\to \tau\nu

We report results of a search for $B\to\tau\nu$ in a sample of 9.7 million charged $B$ meson decays. The search uses both $\pi\nu$ and $\ell\nu\bar\nu$ decay modes of the $\tau$, and demands exclusive reconstruction of the companion $\bar B$ decay to suppress background. We set an upper limit on the branching fraction ${\cal B}(B\to \tau\nu) < 8.4\times 10^{-4}$ at 90% confidence level. With slight modification to the analysis we also establish ${\cal B}(B^\pm\to K^\pm\nu\bar\nu) < 2.4\times 10^{-4}$ at 90% confidence level.Comment: 10 ages postscript, also available through http://w4.lns.cornell.edu/public/CLN

Precise Measurement of B^{0}\to \bar{B^{0} Mixing Parameters at the Υ(\Upsilon(S)$

We describe a measurement of B^0-B^0bar mixing parameters exploiting a method of partial reconstruction of the decay chains B0 -> D^{*-}\pi^+ and B0 -> D^{*-}\rho^+. Using 9.6 x 10^6 BBbar pairs collected at the Cornell Electron Storage Ring, we find \chi_d = 0.198 +- 0.013 +- 0.014, |y_d|<0.41 at 95% confidence level, and |Re(\epsilon_B)|<0.034 at 95% confidence level.Comment: 11 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

Measurement of B(/\c->pKpi)

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)

Measurements of charm fragmentation into D-s(*+) and D-s(+) in e(+)e(-) annihilations at root s=10.5 GeV

A study of charm fragmentation into Ds*+ and Ds+ 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(Ds*+) and σ(Ds+) in momentum regions above x=0.44, where x is the Ds momentum divided by the maximum kinematically allowed Ds momentum. The Ds vector to vector plus pseudoscalar production ratio is measured to be PV(x(Ds+)&gt;0.44)=0.44±0.04. ©2000 The American Physical Society

Resonant structure of τ→3 ππ0ντ and τ→ωπντ decays

The resonant structure of the four pion final state in the decay τ→3 ππ0ντ has been analyzed using 4.27 million τ+τ- pairs collected by the CLEO II experiment at the Cornell Electron Storage Ring. A partial wave analysis of the resonant structure of the τ→3 ππ0ντ decay has been performed; the spectral decomposition of the four pion system is dominated by the ωπ and a1π final states. The mass and width of the ρ′ resonance have been extracted from a fit to the τ→ωπντ spectral function. We have searched for second class currents in the decay τ→ωπντ using spin-parity analysis and established an upper limit on the non-vector current contribution. © 2000 The American Physical Society

Search for B -&gt;tau nu and B -&gt; K nu(nu)over-bar

We report results of a search for B--&gt;tau(nu) in a sample of 9.7 x 10(6) charged B meson decays. We exclusively reconstruct the companion B decay to suppress background. We set an upper limit on the branching fraction B(B--&gt;tau(nu))&lt;8.4 x 10(-4) at 90% confidence level. We also establish B(B+/---&gt;K+/-nu(nu))&lt;2.4 x 10(-4) at 90% confidence level

Search for the decay (B)over-bar(0) -&gt; D*(0)gamma

We report results of a search for the rare radiative decay B̄0 → D0γ. Using 9.66 × 10 6 BB̄ meson pairs collected with the CLEO detector at the Cornell Electron Storage Ring, we set an upper limit on the branching ratio for this decay of 5.0× 10-5 at 90% C.L. This provides evidence that the anomalous enhancement is absent in W-exchange processes and that weak, radiative B decays are dominated by the short-distance b → sγ mechanism in the standard model. © 2000 The American Physical Society