Malcolm John

Abstract:

We search for the rare leptonic decay B+→τ+ντ in a sample of 232×106 BB̄ pairs collected with the BABAR detector at the SLAC PEP-II B-Factory. Signal events are selected by examining the properties of the B meson recoiling against the semileptonic decay B-→D*0-ν̄. We find no evidence for a signal and set an upper limit on the branching fraction of B(B+→τ+ντ)<2.8×10-4 at the 90% confidence level. We combine this result with a previous, statistically independent BABAR search for B+→τ+ντ to give an upper limit of B(B+→τ+ντ)<2.6×10-4 at the 90% confidence level. © 2006 The American Physical Society.

Abstract:

We present the results of a search for the decay B0→τ+τ- in a data sample of (232±3)×106 Υ(4S)→BB̄ decays using the BABAR detector. Certain extensions of the standard model predict measurable levels of this otherwise rare decay. We reconstruct fully one neutral B meson and seek evidence for the signal decay in the rest of the event. We find no evidence for signal events and obtain B(B0→τ+τ-)<4.1×10-3 at the 90% confidence level. © 2006 The American Physical Society.

Abstract:

We present branching fraction measurements of 12 B meson decays of the form B→D(*)Ds(J)(*). The results are based on Υ(4S) decays in BB̄ pairs. One of the B mesons is fully reconstructed and the other decays to two charm mesons, of which one is reconstructed, and the mass and momentum of the other is inferred by kinematics. Combining these results with previous exclusive branching fraction measurements, we determine B(Ds-→ π-)=(4.62±0.36stat.±0.51syst.)%, B(DsJ(2460)-→Ds*- π0)=(56±13stat.±9syst.)% and B(DsJ(2460)-→Ds-γ)= (16±4stat.±3syst.)%. © 2006 The American Physical Society.

Abstract:

The e+e-→pp̄ cross section is determined over a range of pp̄ masses, from threshold to 4.5GeV/c2, by studying the e+e-→pp̄γ process. The data set corresponds to an integrated luminosity of 232fb-1, collected with the BABAR detector at the PEP-II storage ring, at an e+e- center-of-mass energy of 10.6 GeV. The mass dependence of the ratio of electric and magnetic form factors, |GE/GM|, is measured for pp̄ masses below 3GeV/c2; its value is found to be significantly larger than 1 for masses up to 2.2GeV/c2. We also measure J/ψ→pp̄ and ψ(2S)→pp̄ branching fractions and set an upper limit on Y(4260)→pp̄ production and decay. © 2006 The American Physical Society.

Abstract:

We present results of a search for the X(3872) in B0→X(3872)KS0, X(3872)→J/ψπ+π-, improved measurements of B-→X(3872)K-, and a study of the J/ψπ+π- mass region above the X(3872). We use 232×106 BB̄ pairs collected at the Υ(4S) resonance with the BABAR detector at the PEP-II e+e- asymmetric-energy storage rings. The results include the 90% confidence interval 1.34×10-6

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