G. P. Dubois

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.

Measurement of the inclusive decay properties of charmed mesons

Abstract We report a high statistics study of the inclusive decay properties of the charmed D0 and D+ mesons, and the first inclusive study of the charmed Ds+. The data are collected at s =3.77 GeV and s =4.14 GeV with the Mark III detector at the e+e− storage ring SPEAR. For each charmed meson species, the charged-particle multiplicity, the strangeness content of the final state, and the average π0 multiplicity are determined.

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^*

We present a study of the radiative decay J/ψ→γOO in the γK + K − K + K − and γK + K − K S 0 K L 0 final states. A pseudoscalar state is observed in the OO invariant-mass spectrum at 2.22 GeV/c 2 with a width of 150 MeV/c 2 . The product branching ratios are B(J/ψ→γX)B(X→OO)=(3.3±0.8±0.5)×10 −4 for the MeV/c γK + K − K + K − mode and B(J/ψ→γX)B(X→OO)=(2.7±0.6±0.6)×10 −4 for the γK + K − K S 0 K L 0 mode. No evidence for 2 ++ states below 2.4 GeV/c 2 is found in this decay

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.

Observation of a pseudoscalar state in J/ psi --> gamma phi phi near phi phi threshold.

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 ☆

We present a study of the radiative decay J/ψ→γOO in the γK + K − K + K − and γK + K − K S 0 K L 0 final states. A pseudoscalar state is observed in the OO invariant-mass spectrum at 2.22 GeV/c 2 with a width of 150 MeV/c 2 . The product branching ratios are B(J/ψ→γX)B(X→OO)=(3.3±0.8±0.5)×10 −4 for the MeV/c γK + K − K + K − mode and B(J/ψ→γX)B(X→OO)=(2.7±0.6±0.6)×10 −4 for the γK + K − K S 0 K L 0 mode. No evidence for 2 ++ states below 2.4 GeV/c 2 is found in this decay