The four LEP collaborations, ALEPH, DELPHI, L3 and OPAL, have searched for the neutral Higgs bosons which are predicted by the Minimal Supersymmetric Standard Model (MSSM). The data of the four collaborations are statistically combined and examined for their consistency with the background hypothesis and with a possible Higgs boson signal. The combined LEP data show no significant excess of events which would indicate the production of Higgs bosons. The search results are used to set upper bounds on the cross-sections of various Higgs-like event topologies. The results are interpreted within the MSSM in a number of "benchmark" models, including CP-conserving and CP-violating scenarios. These interpretations lead in all cases to large exclusions in the MSSM parameter space. Absolute limits are set on the parameter tan β and, in some scenarios, on the masses of neutral Higgs bosons.

We present a new measurement of the inclusive and differential production cross sections of J= mesons and b hadrons in proton-antiproton collisions at s p 1960 GeV. The data correspond to an integrated luminosity of 39:7 pb ÿ1 collected by the CDF run II detector. We find the integrated cross section for inclusive J= production for all transverse momenta from 0 to 20 GeV=c in the rapidity range jyj < 0:6 to be 4:08 0:02stat 0:36 ÿ0:33 syst b. We separate the fraction of J= events from the decay of the long-lived b hadrons using the lifetime distribution in all events with p T J= > 1:25 GeV=c. We find the total cross section for b hadrons, including both hadrons and antihadrons, decaying to J= with transverse momenta greater than 1:25 GeV=c in the rapidity range jyJ= j < 0:6 is 0:330 0:005stat 0:036 ÿ0:033 syst b. Using a Monte Carlo simulation of the decay kinematics of b hadrons to all final states containing a J= , we extract the first measurement of the total single b-hadron cross section down to zero transverse momentum at s p 1960 GeV. We find the total single b-hadron cross section integrated over all transverse momenta for b hadrons in the rapidity range jyj < 0:6 to be 17:6 0:4stat 2:5 ÿ2:3 syst b.

In this Report, QCD results obtained from a study of hadronic event structure in high energy e+e− interactions with the L3 detector are presented. The operation of the LEP collider at many different collision energies from 91 to 209 GeV offers a unique opportunity to test QCD by measuring the energy dependence of different observables. The main results concern the measurement of the strong coupling constant, alpha_s, from hadronic event shapes and the\ud study of effects of soft gluon coherence in charged particle multiplicity and momentum distributions

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Single- and multi-photon events with missing energy are selected in 619 pb−1 of data collected by the L3 detector at LEP at centre-of-mass energies between 189 GeV and 209 GeV. The cross sections of the process e+e− → vv-bar gamma (gamma) are found to be in agreement with the Standard Model expectations, and the number of light neutrino species is determined, including lower energy data, to be N = 2.98 +/- 0.05 +/- 0.04.\ud Selection results are given in the form of tables which can be used to test future models involving single- and multi-photon signatures at LEP. These final states are also predicted by models with large extra dimensions and by several supersymmetric\ud models. No evidence for such models is found. Among others, lower limits between 1.5 TeV and 0.65 TeV are set, at 95% confidence level, on the new scale of gravity for the number of extra dimensions between 2 and 8