Malcolm John

Abstract:

We present a measurement of the partial branching fractions and mass spectra of the exclusive radiative penguin processes B→Kππγ in the range mKππ<1.8GeV/c2. We reconstruct four final states: K+π-π+γ, K+π-π0γ, KS0π-π+γ, and KS0π+π0γ, where KS0→π+π-. Using 232×106 e+e-→BB̄ events recorded by the BABAR experiment at the SLAC PEP-II asymmetric-energy storage ring, we measure the branching fractions B(B+→K+π-π+γ)=[2.95±0.13(stat)±0.20(syst)] ×10-5, B(B0→K+π-π0γ)=[4.07±0.22(stat)±0. 31(syst)]×10-5, B(B0→K0π+π-γ)=[1.85±0.21(stat) ±0.12(syst)]×10-5, and B(B+→K0π+π0γ)=[4. 56±0.42(stat)±0.31(syst)]×10-5. © 2007 The American Physical Society.

Abstract:

We present a measurement of the cross section of the process e+e-→π+π-ψ(2S) from threshold up to 8 GeV center-of-mass energy using events containing initial-state radiation, produced at the SLAC PEP-II e+e- storage rings. The study is based on 298fb-1 of data recorded with the BABAR detector. A structure is observed in the cross section not far above threshold, near 4.32 GeV. We also investigate the compatibility of this structure with the Y(4260) previously reported by this experiment. © 2007 The American Physical Society.

Abstract:

We report on a study of inclusive B- and B̄0 meson decays to D0X, D̄0X, D+X, D-X, Ds+X, Ds-X, Λc+X, Λ̄c-X, based on a sample of 231×106 BB̄ events recorded with the BABAR detector at the Υ(4S) resonance. Events are selected by completely reconstructing one B and searching for a reconstructed charm particle in the rest of the event. From the measured branching fractions of these decays, we infer the number of charm and anticharm particles per B̄ decay, separately for charged and neutral parents. We derive the total charm yield per B- decay, nc-=1.208±0. 023±0.040-0.029+0.035, and per B̄0 decay, nc0=1.203±0. 030±0.034-0.035+0.044 where the first uncertainty is statistical, the second is systematic, and the third reflects the charm branching-fraction uncertainties. We also present the charm momentum distributions measured in the B̄ rest frame. © 2007 The American Physical Society.

Abstract:

Using 230.2fb-1 of e+e- annihilation data collected with the BABAR detector at and near the peak of the Υ(4S) resonance, 489±55 events containing the pure leptonic decay Ds+→μ+νμ have been isolated in charm-tagged events. The ratio of partial widths Γ(Ds+→μ+νμ) /Γ(Ds+→ π+) is measured to be 0.143±0.018±0.006 allowing a determination of the pseudoscalar decay constant fDs= (283±17±7±14)MeV. The errors are statistical, systematic, and from the Ds+→ π+ branching ratio, respectively. © 2007 The American Physical Society.

Abstract:

We measure the branching ratios of the Cabibbo-suppressed decays Λc+→ΛK+ and Λc+→Σ0K+ relative to the Cabibbo-favored decay modes Λc+→Λπ+ and Λc+→Σ0π+ to be 0.044±0.004(stat.)±0.003(syst. ) and 0.038±0.005(stat.)±0.003(syst.), respectively. We set an upper limit on the branching ratio at the 90% confidence level for Λc+→ΛK+π+π- of 4.1×10-2 relative to Λc+→Λπ+, and for Λc+→Σ0K+π+π- of 2.0×10-2 relative to Λc+→Σ0π+. We also measure the branching fraction for the Cabibbo-favored mode Λc+→Σ0π+ relative to Λc+→Λπ+ to be 0.977±0.015(stat.) ±0.051(syst.). This analysis was performed using a data sample with an integrated luminosity of 125fb-1 collected by the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. © 2007 The American Physical Society.