The B0and B+meson lifetimes have been measured in e+e- annihilation data collected in 1999 and 2000 with the BABAR detector at center-of-mass energies near the γ(4S) resonance. Events are selected in which one B meson is fully reconstructed in a hadronic final state while the second B meson is reconstructed inclusively. A combined fit to the B0and the B+decay time difference distributions yields τB0= 1.546 ± 0.032(stat) ± 0.022(syst) ps, τB+= 1.673 ± 0.032(stat) ± 0.023(syst) ps, and τB+/τB0= 1.082 ± 0.026(stat) ± 0.012(syst). © 2001 The American Physical Society.

We present the results of searches for B decays to charmless two-body final states containing η′ or ω mesons, based on 50.7fb-1of data collected with the BABAR detector. We find the branching fractions B(B+→ η′K+) = (70 ± 8 ± 5) × 10-6, B(B0→ η′K0) = (42+13-11± 4) × 10-6, and B(B+→ ωπ+) = (6.6+2.1-1.8± 0.7) × 10-6, where the first error quoted is statistical and the second is systematic. We give measurements of four additional modes for which the 90% confidence level upper limits are B(B+→ η′π+) < 12 × 10-6, B(B+→ ωK+) < 4 × 10-6, B(B0→ ωK0) < 13 × 10-6, and B(B0→ ωπ0) < 3 × 10-6. © 2001 The American Physical Society.

The production of J/ψ mesons in continuum e+e- annihilations has been studied with the BABAR detector at energies near the Υ(4S) resonance. The mesons are distinguished from J/ψ production in B decays through their center-of-mass momentum and energy. We measure the cross section e+e- → J/ψX to be 2.52 ± 0.21 ± 0.21pb. We set a 90% C.L. upper limit on the branching fraction for direct Υ(4S) → J/ψX decays at 4.7 × 10-4. © 2001 The American Physical Society.