Malcolm John

Abstract:

Branching fraction and asymmetry measurements of charmless B+→K*+h1+h2- (where h1,2=K, π) decays are presented, using a data sample of 232×106 Υ(4S)→BB̄ decays collected with the BABAR detector at the SLAC PEP-II asymmetric-energy B factory. Using a maximum likelihood fit, the following branching fraction results were obtained: B(B+→K*+K+K-)=(36.2±3.3±3.6)×10-6 and B(B+→K*+π+π-)=(75.3±6.0±8.1)×10-6. Upper limits were set for B(B+→K*+π+K-)<11.8×10-6 and B(B+→K*+K+π-)<6.1×10-6 at 90% confidence level. The charge asymmetries for the decays B+→K*+K+K- and B+→ K*+π+π- were measured to be AK*KK=0.11±0.08±0.03 and AK*ππ=0.07±0.07±0.04, respectively. The first error quoted on branching fraction and asymmetry measurements is statistical and the second systematic. © 2006 The American Physical Society.

Abstract:

We analyze the three-body charmless decay B±→K±K± K using a sample of 226.0±2.5 million BB̄ pairs collected by the BABAR detector. We measure the total branching fraction and CP asymmetry to be B=(35.2±0.9±1.6)×10-6 and ACP=(-1.7±2.6±1.5)%. We fit the Dalitz plot distribution using an isobar model and measure the magnitudes and phases of the decay coefficients. We find no evidence of CP violation for the individual components of the isobar model. The decay dynamics is dominated by the K+K- S-wave, for which we perform a partial-wave analysis in the region m(K+K-)<2GeV/c2. Significant production of the f0(980) resonance, and of a spin zero state near 1.55GeV/c2 are required in the isobar model description of the data. The partial-wave analysis supports this observation. © 2006 The American Physical Society.

Abstract:

We report two novel determinations of |Vub| with reduced model dependence, based on measurements of the mass distribution of the hadronic system in semileptonic B decays. Events are selected by fully reconstructing the decay of one B meson and identifying a charged lepton from the decay of the other B meson from Υ(4S)→BB̄ events. In one approach, we combine the inclusive B̄→Xuν̄ rate, integrated up to a maximum hadronic mass mX<1.67GeV/c2, with a measurement of the inclusive B→Xsγ photon energy spectrum. We obtain |Vub|=(4.43±0.38stat±0.25syst±0.29theo)×10-3. In another approach we measure the total B̄→Xuν̄ rate over the full phase space and find |Vub|=(3.84±0.70stat±0.30syst±0.10theo)×10-3. © 2006 The American Physical Society.