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Abstract:

The disappearance decays of B0 mesons, where the B0 decay contains no observable final state particles or invisible decay products with a single photon, was investigated. The decays have branching fractions below the experimental sensitivity and physics models are used to predict significant contributions from these channels. The limits on branching fractions for B0 decays to an invisible final state and for B0 decays to vv̄y branching fractions.

Abstract:

The time-dependent decay rate for the process B→J/ψK *(892) in γ(4S)→BB̄ decays detected by BABAR detector, was investigated. The flavor-tagged events, where one neutral B meson was reconstructed in the J/ψK*0 or J/ψK̄ *0 final state, were observed. The coefficients of cosine and sine terms in time-dependent asymmetries were also measured. The results show that for a single ratio of wrong-flavor to favored amplitudes for B0 and ̄0 combined, an upper limit of 0.25 at 90% confidence level (C.L.) was obtained.

Abstract:

We present measurements of the branching fractions and charge asymmetries (where appropriate) of two-body B decays to η(′) K*, η(′) ρ, η(′) π0, ωπ0, and φπ0. The data were recorded with the BABAR detector at PEP-II and correspond to 89×106 BB pairs produced in e +e- annihilation through the Υ (4S) resonance. We find significant signals for two decay modes and measure the branching fractions B(B+→ηK*+)=(25.6 ±4.0±2.4) ×10-6 and B(B0→ηK*0) = (18.6±23±1.2)×10-6, where the first error is statistical and the second systematic. We also find evidence with significance 3,5σ for a third decay mode and measure B(B+ →ηρ+)=(9.2±3.4±1.0)×10 -6. For other channels, we set 90% C.L. upper limits of B(B 0→ηρ0)<1.5 ×10-6, B(B+→η′K*+)<14×10 -6, B(B0→η′K*0)<7. 6×10-6, B(B0→η′K*0) <22×10-6, B(B0 →η′ρ 0)<4.3×10-6, B(B0→ηπ 0)<2.5×10-6, B(B0→η′ π0)<3.7×10-6, B(B0→ωπ 0)<1.2×10-6, and B(B0→φπ 0)<1.0×10-6. For self-flavor-tagging modes with significant signals, the time-integrated charge asymmetries are A ch(ηK*+)=+0.13±0.14±0.02 and Ach(ηK*0)=+0.02±0.11±0.02.

Abstract:

The branching fraction for the semi-inclusive process B→ήXs, where Xs is a strange hadronic system, was measured. The Xs mass spectrum was also obtained, which fits into models predicting high masses. Two tracking devices, a silicon vertex tracker consisting of five layers of double-sided silicon microstrip detectors and a 40-layer central drift chamber, were used for the detection of charged particles. It was found that the charged-particle identification was provided by the average energy loss in the tracking devices.