D.H. Coward

Measurement of the Branching Fractions for D0 ---> pi- e+ electron-neutrino and D0 ---> K- e+ electron-neutrino and Determination of (V (c d) / V (c s))**2

Measurements of the exclusive branching fractions B(D^0→π^-e^+ν_e) and B(D^0→K^-e^+ν_e), using data collected at the ψ(3770) with the Mark III detector at the SLAC e^+e^- storage ring SPEAR, are used to determine the ratio of the Kobayashi-Maskawa matrix elements │V_(cd)/V_(cs)│^2 =0.057_(-0.015)^(+0.038)±0.005.

Resonant substructure in Kππ decays of charmed D mesons

Abstract Dalitz plot analyses of four Kππ decays of the D 0 and D + mesons are presented. The relative amounts of K ∗ π, Kϱ and non-resonant Kππ in each decay mode are determined, and isospin amplitudes and phases are derived. These results are compared with predictions from QCD. The K − π + π + mode has a non-uniform, non-resonant contribution; attempts to fit this distribution are described.

Measurement of the

We report a new measurement of the D∗ branching ratios, using data obtained with the Mark III detector at the e^+e^− storage ring SPEAR at s=4.14GeV. A fit to the recoil mass squared spectrum of D mesons reconstructed through the decay modes K^−π^+π^+ and K^−π^+ is used to extract the D^(∗+) → γD^+, π^0D^+, π^+D^0 and D^(∗0) → γD^0, π^0D^0 branching ratios.

D^*

Abstract This paper describes the design, construction and performance of the Mark III, a new general purpose large solid angle spectrometer at SPEAR, the SLAC 2–8 GeV e+e− storage ring. The detector has been designed for the study of exclusive final states in e+e− annihilation, which requires large solid angle coverage combined with charged particle momentum resolution, particle identification, and photon detection efficiency at low energies.

Branching Ratios

We determine the resonant substructure of D -> [...] decays using a five-dimensional maximum likelihood technique to extract the relative fractions and phases of the amplitudes contributing to the [...], [...], and [...] final states. We find that two-body decay modes account for about 75% of these decays. We obtain branching ratios for [...], [...], [...], [...], and [...] decay modes, as well as several three and four-body decay modes. In the case of [...] and [...], we obtain the branching ratios for all three possible isospin combinations, enabling us to extract the isospin 1/2 and 3/2 amplitudes. This allows us to eliminate the ambiguity due to phase shifts between the isospin amplitudes when comparing our results with theoretical models. We find that the isospin 3/2 amplitudes are suppressed relative to the isospin 1/2 amplitudes, confirming that an understanding of the lifetime difference of the D0 and D+ depends on an understanding of two-body hadronic decays. For the [...] decay modes, we obtain detailed information on the polarization of the [...] and [...]. This enables us to obtain information on form-factors for [...] and [...] transitions, within the context of the factorization hypothesis. Comparison of our results on [...] decays with recent results on semileptonic decays allows us to test the factorization hypothesis.

The Mark III spectrometer

Abstract A search for the lepton family number violating decay D 0 → μ e is reported. No signal is observed in a data sample of 9.3 pb −1 collected at the ζ (3770) resonance with the MARK III detector, where 0.18±0.06±0.05 background events are expected. A 90% confidence level upper limit on the branching fraction B (D 0 → μ e) of 1.5 × 10 −4 is obtained.

Resonant substructure in K[over ¯]πππ decays of D mesons

Abstract We present an analysis of J ψ →γf 1 (1285) , f 1 (1285)→ π + π − π + π − , using the Mark III detector at SPEAR, based on 5.8 × 10 6 produced J ψ events. We measure B( J ψ →γf 1 (1285) , f 1 (1285)→ π + π − π + π − )=(4.8±1.3±0.9) × 10 −5 . We obtain a new measurement of the absolute branching ratio of J ψ →γf 1 (1285) . The mixing angle of the f 1 (1285) and the f 1 (1420) in the 1 ++ nonet is determined.

A search for the lepton family number violating decay D0→μe

We determine the resonant substructure of D -> [...] decays using a five-dimensional maximum likelihood technique to extract the relative fractions and phases of the amplitudes contributing to the [...], [...], and [...] final states. We find that two-body decay modes account for about 75% of these decays. We obtain branching ratios for [...], [...], [...], [...], and [...] decay modes, as well as several three and four-body decay modes. In the case of [...] and [...], we obtain the branching ratios for all three possible isospin combinations, enabling us to extract the isospin 1/2 and 3/2 amplitudes. This allows us to eliminate the ambiguity due to phase shifts between the isospin amplitudes when comparing our results with theoretical models. We find that the isospin 3/2 amplitudes are suppressed relative to the isospin 1/2 amplitudes, confirming that an understanding of the lifetime difference of the D0 and D+ depends on an understanding of two-body hadronic decays. For the [...] decay modes, we obtain detailed information on the polarization of the [...] and [...]. This enables us to obtain information on form-factors for [...] and [...] transitions, within the context of the factorization hypothesis. Comparison of our results on [...] decays with recent results on semileptonic decays allows us to test the factorization hypothesis.

Observation of f1(1285)→π+π−π+π− in radiative decays ☆

The BaBar Drift Chamber is now under construction. We review its design, the progress in the construction of the components, the plan for assembly and stringing and we present test results obtained with a prototype exposed at SLAC to cosmic rays. We also report on projected dE/dx performance from beam tests done with a chamber with a different cell design.

Resonant substructure in K decays of D mesons

Abstract We present results on energy resolution and linearity, and position resolution, from a test of an array of CsI(T1) crystals in a π/e/μ beam (120 to 400 MeV) at TRIUMF. The crystal array was designed to study the effects of longitudinal and transverse crystal segmentation on energy and position resolution and background rejection. We also studied the feasibility of a wavelength-shifter and multi-photodiode readout system, suitable for use in magnetic detectors at low and medium energy, high-luminosity e+e− storage rings. Energy resolutions of (1.69±0.08)% √E( GeV ) and (1.83±0.05)% √E( GeV ) were obtained for two different crystal tower configurations. Position resolution of 6.5 (9.0) mm was obtained at 300 (120) MeV for a 2 × 2 square array of four 4 × 4 × 7.4 cm3 crystals transverse to the beam.