Malcolm John

Abstract:

We present measurements of branching fractions of B0 decays to multibody final states containing protons, based on 232×106 Υ(4S)→BB̄ decays collected with the BABAR detector at the SLAC PEP-II asymmetric-energy B factory. We measure the branching fractions B(B0→D̄0pp̄)=(1. 13±0.06±0.08)×10-4, B(B0→D̄*0pp̄)=(1. 01±0.10±0.09)×10-4, B(B0→D-pp̄π+)=(3. 38±0.14±0.29)×10-4, and B(B0→D*-pp̄π+)= (4.81±0.22±0.44)×10-4 where the first error is statistical and the second systematic. We present a search for the charmed pentaquark state, Θc(3100) observed by H1 and put limits on the branching fraction B(B0→Θcp̄π+)×B(Θc→D*-p) <14×10-6 and B(B0→Θcp̄π+)×B(Θc→D-p) <9×10-6. Upon investigation of the decay structure of the above four B0 decay modes, we see an enhancement at low pp̄ mass and deviations from phase-space in the D̄p̄ and D̄p invariant mass spectra. © 2006 The American Physical Society.

Abstract:

We measure the dependence of B̄0→D*+e-ν̄e on the decay angles and momentum transfer. The data sample consists of ∼86×106 BB̄-pairs accumulated on the Υ(4S) resonance by the BABAR detector at the asymmetric e+e- collider PEP-II. We specify the three form factors by two ratios R1 and R2, and by a single parameter ρ2 characterizing the polynomial representing hA1, the function which describes the momentum-transfer dependence of the form factor A1. We determine R1, R2, and ρ2 using an unbinned maximum likelihood fit to the full decay distribution. The results are R1=1.396±0.060±0.035±0.027, R2=0.885±0.040±0.022±0.013, and ρ2=1.145±0. 059±0.030±0.035. The stated uncertainties are the statistical from the data, statistical from the size of the Monte Carlo sample and the systematic uncertainty, respectively. In addition, based on this measurement, we give an updated value for the CKM matrix element |Vcb|. © 2006 The American Physical Society.

Abstract:

We present a measurement of the branching fraction of the decay B0→a1±(1260)π with a1±(1260) →ππ±π±. The data sample corresponds to 218×106 BB̄ pairs produced in e+e- annihilation through the Υ(4S) resonance. We measure the branching fraction B(B0→a1±(1260)π) B(a1±(1260)→ππ±π±)=(16.6±1.9±1. 5)×10-6, where the first error quoted is statistical and the second is systematic. © 2006 The American Physical Society.

Abstract:

We observe a new Ds meson with mass (2856.6±1. 5stat±5.0syst)MeV/c2 and width (48±7stat ±10syst)MeV/c2 decaying into D0K+ and D+KS0. In the same mass distributions, we also observe a broad structure with mass (2688± 4stat±3syst)MeV/c2 and width (112±7stat ±36syst)MeV/c2. To obtain this result, we use 240fb-1 of data recorded by the BABAR detector at the PEP-II asymmetric-energy e+e- storage rings at the Stanford Linear Accelerator Center running at center-of-mass energies near 10.6 GeV. © 2006 The American Physical Society.

Abstract:

We report the first observation of e+e- annihilation into states of positive C parity, namely, ρ0ρ0 and ρ0. The two states are observed in the π+π-π+π- and K+K-π+π- final states, respectively, in a data sample of 225fb-1 collected by the BABAR experiment at the Positron-Electron Project II e+e- storage rings at energies near s=10.58GeV. The distributions of cos θ*, where θ* is the center-of-mass polar angle of the meson or the forward ρ0 meson, suggest production by two-virtual-photon annihilation. We measure cross sections within the range |cos θ*|<0.8 of σ(e+e-→ρ0ρ0)=20.7±0.7(stat) ±2.7(syst)fb and σ(e+e-→ρ0)=5.7±0.5(stat)±0. 8(syst)fb. © 2006 The American Physical Society.