D. G. Cassel

First measurement of Γ(D* +) and precision measurement of m D*+-m D0

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^2

Model-independent determination of the strong-phase difference between D0 and D⊃̄0→KS,L0h+h- (h=π, K) and its impact on the measurement of the CKM angle γ/Φ3

We report the first determination of the relative strong-phase difference between D0→KS,L0K+K- and D 0→KS,L0K+K-. In addition, we present updated measurements of the relative strong-phase difference between D0→KS,L0π+π- and D 0→KS,L0π+π-. Both measurements exploit the quantum coherence between a pair of D0 and D 0 mesons produced from ψ(3770) decays. The strong-phase differences measured are important for determining the Cabibbo-Kobayashi-Maskawa angle γ/ϕ3 in B-→K-D˜0 decays, where D˜0 is a D0 or D 0 meson decaying to KS0h+h- (h=π, K), in a manner independent of the model assumed to describe the D0→KS0h+h- decay. Using our results, the uncertainty in γ/ϕ3 due to the error on the strong-phase difference is expected to be between 1.7° and 3.9° for an analysis using B-→K-D˜0, D˜0→KS0π+π- decays, and between 3.2° and 3.9° for an analysis based on B-→K-D˜0, D˜0→KS0K+K- decays. A measurement is also presented of the CP-odd fraction, F-, of the decay D0→KS0K+K- in the region of the ϕ→K+K- resonance. We find that in a region within 0.01  GeV2/c4 of the nominal ϕ mass squared F->0.91 at the 90% confidence level.

Improved measurements of D meson semileptonic decays to π and K mesons

Using the entire CLEO-c {psi}(3770){yields}DD event sample, corresponding to an integrated luminosity of 818 pb{sup -1} and approximately 5.4x10{sup 6} DD events, we present a study of the decays D{sup 0}{yields}{pi}{sup -}e{sup +}{nu}{sub e}, D{sup 0}{yields}K{sup -}e{sup +}{nu}{sub e}, D{sup +}{yields}{pi}{sup 0}e{sup +}{nu}{sub e}, and D{sup +}{yields}K{sup 0}e{sup +}{nu}{sub e}. Via a tagged analysis technique, in which one D is fully reconstructed in a hadronic mode, partial rates for semileptonic decays by the other D are measured in several q{sup 2} bins. We fit these rates using several form factor parametrizations and report the results, including form factor shape parameters and the branching fractions B(D{sup 0}{yields}{pi}{sup -}e{sup +}{nu}{sub e})=(0.288{+-}0.008{+-}0.003)%, B(D{sup 0}{yields}K{sup -}e{sup +}{nu}{sub e})=(3.50{+-}0.03{+-}0.04)%, B(D{sup +}{yields}{pi}{sup 0}e{sup +}{nu}{sub e})=(0.405{+-}0.016{+-}0.009)%, and B(D{sup +}{yields}K{sup 0}e{sup +}{nu}{sub e})=(8.83{+-}0.10{+-}0.20)%, where the first uncertainties are statistical and the second are systematic. Taking input from lattice quantum chromodynamics, we also find |V{sub cd}|=0.234{+-}0.007{+-}0.002{+-}0.025 and |V{sub cs}|=0.985{+-}0.009{+-}0.006{+-}0.103, where the third uncertainties are from lattice quantum chromodynamics.

The CLEO detector

Abstract The construction and performance of a large aperture magnetic detector designed for use at the Cornell Electon Storage Ring is descr bed.

Branching fractions of τ Leptons to three charged Hadrons

From electron-positron collision data collected with the CLEO detector operating at Cornell Electron Storage Ring near sqrt[s]=10.6 GeV, improved measurements of the branching fractions for tau decays into three explicitly identified hadrons and a neutrino are presented as B(tau(-)-->pi(-)pi(+)pi(-)nu(tau))=(9.13+/-0.05+/-0.46)%, B(tau(-)-->K-pi(+)pi(-)nu(tau))=(3.84+/-0.14+/-0.38) x 10(-3), B(tau(-)-->K-K+pi(-)nu(tau))=(1.55+/-0.06+/-0.09) x 10(-3), and B(tau(-)-->K-K+K-nu(tau))<3.7 x 10(-5) at 90% C.L., where the uncertainties are statistical and systematic, respectively.

Measurements of D meson decays to two pseudoscalar mesons

Using data collected on the {psi}(3770) resonance and near the D{sub s}*{sup {+-}D}{sub s}{sup {+-}}peak production energy by the CLEO-c detector, we study the decays of the possible D{yields}PP modes and report measurements of or upper limits on all branching fractions for Cabibbo-favored, singly Cabibbo-suppressed, and doubly Cabibbo-suppressed D{yields}PP decays except modes involving K{sub L}{sup 0} (and except D{sup 0{yields}}K{sup +{pi}-}). We normalize with respect to the Cabibbo-favored D modes, D{sup 0{yields}}K{sup -{pi}+}, D{sup +{yields}}K{sup -{pi}+{pi}+}, and D{sub s}{sup +{yields}}K{sup +}K{sub S}{sup 0}.

Measurement of the ηb(1S) mass and the branching fraction for Υ(3S)→γηb(1S)

We report evidence for the ground state of bottomonium, eta_b(1S), in the radiative decay Upsilon(3S) --> gamma eta_b in e^+e^- annihilation data taken with the CLEO III detector. Using 6 million Upsilon(3S) decays, and assuming Gamma(eta_b) = 10 MeV/c^2, we obtain B(Upsilon(3S) --> gamma eta_b) = (7.1 +- 1.8 +- 1.1) X 10^{-4}, where the first error is statistical and the second is systematic. The statistical significance is about 4 sigma. The mass is determined to be M(eta_b) = 9391.8 +- 6.6 +- 2.0 MeV/c^2, which corresponds to the hyperfine splitting Delta M_{hf}(1S)_b = 68.5 +- 6.6 +- 2.0 MeV/c^2. Using 9 million Upsilon(2S) decays, we place an upper limit on the corresponding Y(2S) decay, B(Y(2S) --> gamma eta_b) < 8.4 X 10^{-4} at 90 % confidence level.

Limits on rare exclusive decays of B mesons

Abstract We have set upper limits for rare exclusive decays of B mesons arising from higher order processes in the standard model of electroweak interactions. Such decays may occur via “penguin diagrams” in B decay. We also set an upper limit on a lepton-number-violating decay mode of the neutral B meson.

Observation of the hc(1P) Using e+e- Collisions above the DD̄ Threshold

Using 586  pb(-1) of e+ e- collision data at E(c.m.) = 4170  MeV, produced at the Cornell Electron Storage Ring collider and collected with the CLEO-c detector, we observe the process e+ e- → π+ π- h(c)(1P). We measure its cross section to be 15.6±2.3±1.9±3.0  pb, where the third error is due to the external uncertainty on the branching fraction of ψ(2S) → π0 h(c)(1P), which we use for normalization. We also find evidence for e+ e- → ηh(c)(1P) at 4170 MeV at the 3σ level and see hints of a rise in the e+ e- → π+ π- h(c)(1P) cross section at 4260 MeV.

Design and construction of the CLEO II drift chamber

Abstract We have constructed a new large cylindrical drift chamber (2 m long and 2 m in diameter) for the CLEO II experiment at the Cornell Electron Storage Ring (CESR). The chamber contains 51 readout layers including 11 stereo layers, with 48480 (12240) total (sense) wires. Segmented cathode strips were used instead of field wires for the innermost and outermost layers to provide two accurate measurements of the longitudinal coordinate. Very low density support structures were developed to hold the cathode strips. Aluminum wire was used for the majority of the field wires to reduce multiple scattering and the tension load on the endplates. A semiautomatic apparatus was developed to string wires with the chamber mounted vertically. With this system, it was also possible to replace any wire in the chamber. A maximum stringing rate of 60 wires/h was achieved. The tension on all wires was measured soon after they were strung; the failure rate due to improper tension was typically less than 2%. Hybrid preamplifiers were developed and mounted directly on the chamber on custom printed circuit boards. Each board also contains a pulser calibration system and a high voltage current monitor. High voltage power is individually supplied to each of the 51 layers under computer control. A new type of hardware track finder was developed for the trigger.