Inclusive J production in Z0 decays

Abstract Inclusive J production in Z 0 decays is observed via the leptonic decay mode J → l + l − (l = e, μ ). We measure the branching ratio Br(Z 0 → J + X) = (4.1 ± 0.7 (stat.) ± 0.3 (sys.)) × 10 −3 . We have calculated the fraction of the J mesons from b-hadron decay and find a branching ratio of Br(b → J + X)= (1.3±0.2(stat.)±0.2(sys.)) × 10 −2 . We determine the average fractional energy of bottom hadrons 〈 X E > = 0.70±0.03 (stat.) +0.02 −0.01 (sys.) using the momentum spectrum of the J mesons. From a study of the angle between the J and the most energetic jet, we set an upper limit on the branching ratio Br ( Z 0 → q q g ∗ ; g ∗ → J + X ) −4 at 90% confidence level.