Malcolm John

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.

Abstract:

We present a study of the decays B̄0→D(*)0K̄(*)0 using a sample of 226×106 Υ(4S)→BB̄ decays collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at SLAC. We report evidence for the decay of B0 and B̄0 mesons to the D*0KS0 final state with an average branching fraction B(B∼0→D*0K∼0) ≡(B(B̄0→D*0K̄0)+B(B0→D*0K0))/2=(3. 6±1.2±0.3)×10-5. Similarly, we measure B(B∼0→ D0K∼0)≡(B(B̄0→D0K̄0)+B(B0→D0K0))/2=(5.3±0. 7±0.3)×10-5 for the D0KS0 final state. We measure B(B̄0→D0K̄*0)=(4.0±0.7±0.3)×10-5 and set a 90% confidence level upper limit B(B̄0→D̄0K̄*0) <1.1×10-5. We determine the upper limit for the decay amplitude ratio |A(B̄0→D̄0K̄*0)/A(B̄0→D0K̄*0)| to be less than 0.4 at the 90% confidence level. © 2006 The American Physical Society.

Abstract:

We present measurements of the B→ηKγ branching fractions and upper limits for the B→η′Kγ branching fractions. For B+→ηK+γ we also measure the time-integrated charge asymmetry. The data sample, collected with the BABAR detector at the Stanford Linear Accelerator Center, represents 232×106 produced BB̄ pairs. The results for branching fractions and upper limits at 90% confidence level in units of 10-6 are: B(B0→ηK0γ)=11.3-2.6+2.8±0.6, B(B+→ηK+γ)=10.0±1.3±0.5, B(B0→η′ K0γ)<6.6, B(B+→η′K+γ)<4.2. The charge asymmetry in the decay B+→ηK+γ is Ach=-0.09±0.12±0.01. The first errors are statistical and the second systematic. © 2006 The American Physical Society.