The results of the searches for neutral Higgs boson production in the process e+e---+ Z* Ho are reported, focusing on Higgs boson masses below 70 GeV. The data sample consists of three million hadronic Z" 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 Doublet Model and limits on the nonstandard Higgs boson production through the process e + -e 4 Z* ho are set. A lower limit of 66.7 GeV at 95% CL. is obtained for the case where the Higgs decays into an invisible final state.

A search for exclusive decays of Bt and Bf mesons has been performed in the channels Bi 4 Jq, Bz + Jq Bi 4 Jr0 and Bg -_) J.R'. The data sample consisted of more than three and half million hadronic Z decays collected by the L3 experiment at LEP from 1991 through 1995. No candidate events have been observed for any of the modes thus determining upper limits at 90% confidence level: 3.2 x low4 on Br(Bj --+ Jr') and the first experimental limits: Br(J3: -+ Jv) < 1.2 x 10w3, Br(Bt -+ 57) < 3.8 x 10p3, Br(By -+ Jr') < 1.2 X 10U3.

Using a data sample of 1475 000 Z-f q4(y) events collected during 1994 with the L3 detector at LEP, we have studied the purely leptonic decays of heavy flavour mesons, D;

Single and multi-photon events with missing energy are analysed using data collected with the L3 detector at LEP at a centre-of-mass energy of 189 GeV, for a total of 176 pb y1 of integrated luminosity. The cross section of the process e q e y Ž .™ nng g is measured and the number of light neutrino flavours is determined to be N s 3.011 " 0.077 including lower n energy data. Upper limits on cross sections of supersymmetric processes are set and interpretations in supersymmetric models provide improved limits on the masses of the lightest neutralino and the gravitino. Graviton-photon production in low scale gravity models with extra dimensions is searched for and limits on the energy scale of the model are set exceeding 1 TeV for two extra dimensions.

We report measurements of the inclusive production of heavy quarkonium states in Z decays based on the analysis of 3.6 million hadronic events collected by the L3 detector at LEP. The measurement of inclusive J production and an improved 95% confidence level upper limit on Υ production are presented. In addition, two independent measurements of the ratio, f p , of prompt J mesons to those from B decay are made using two different isolation cuts to separate prompt J mesons from J mesons produced in the decays of b hadrons. The results are:f p = (7.1 ± 2.1 (stat.) ± 1.2 (sys.) +1.5−0.8 (theo.)) × 10 −2 .