Measurement of hadron and lepton-pair production at 161 GeV<root s<172 GeV at LEP

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Inclusive J, Psi' and Chi(c) production in hadronic Z decays

We report on measurements of the inclusive production of J, psi' and chi(c) mesons in hadronic Z decays, based on 3.2 million hadronic events collected using the L3 detector at LEP. The J and psi' mesons are reconstructed through their decays into lepton pairs, while the chi(c) mesons are reconstructed via the decay mode chi(c) --> J + gamma. The measured branching fractions are: Br(Z --> J + X) = (3.40 +/- 0.23 (stat.) +/- 0.27 (sys.)) x 10(-3), Br(Z --> psi' + X) = (1.6 +/- 0.5 (stat.) +/- 0.3 (sys.)) x 10(-3) Br(Z --> chi(cl) + X) = (2.7 +/- 0.6 (stat.) +/- 0.5 (sys.)) x 10(-3). In the absence of a clear chi(c2) signal, the upper limit at 90% C.L. is set: Br(Z --> chi(c2) + X) < 3.2 x 10(-3). (C) 1997 Elsevier Science B.V

Measurement of the B-d(0) meson oscillation frequency

Time-dependent B-d(0)-(B) over bar(d)(0) mixing is studied using 1.5 million hadronic Z decays collected by L3. Semileptonic B decays are selected by requiring at least one reconstructed lepton in both thrust hemispheres. Charge correlations between the tagged leptons are studied as a function of proper time. The proper time of the b-hadron decay is measured by reconstructing the production and decay vertices using a silicon microvertex detector: The measured B-d(0) meson oscillation frequency corresponds to a mass difference Delta m(d) between the two B-d(0) mass eigenstates of Delta m(d) = (0.496(-0.051)(+0.053) (stat) +/- 0.043 (syst)) ps(-1)

Search for neutral Higgs boson production through the process e(+)e(-)->Z(*)H(0)

The results of the searches for neutral Higgs boson production in the process e(+)e(-) --> Z* H-0 are reported, focusing on Higgs boson masses below 70 GeV. The data sample consists of three million hadronic Z(0) decays collected by the L3 experiment at LEP from 1991 through 1994. No signal is found leading to a lower limit on the mass of the Standard Model Higgs boson of 60.2 GeV at 95% C.L. These results are also interpreted in the framework of the General Two Doubler Model and limits on the nonstandard Higgs boson production through the process e(+)e(-) --> Z*h(0) are set. A lower limit of 66.7 GeV at 95% C.L. is obtained for the case where the Higgs decays into an invisible final state