The e + e − → e + e − K 0 S K ± π ∓ and e + e − → e + e − ηπ + π − final states are studied with the L3 detector at LEP using data collected at centre-of-mass energies from 183 GeV up to 202 GeV. The mass spectrum of the K 0 S K ± π ∓ final state shows an enhancement around 1470 MeV, which is identified with the pseudoscalar meson η(1440). This state is observed in γ γ collisions for the first time and its two-photon width is measured to be Γ γ γ (η( 1440)) × BR(η(1440) → K Kπ) = 212 ± 50 (stat.) ± 23 (sys.) eV. Clear evidence is also obtained for the formation of the axial vector mesons f 1 (1420) and f 1 (1285). In the ηπ + π − channel the f 1 (1285) is observed, and upper limits for the formation of η(1440) and η(1295) are obtained.

The K 0 S K 0 S final state in two-photon collisions is studied with the L3 detector at LEP. The mass spectrum is dominated by the formation of the f 2 (1525) tensor meson in the helicity-two state with a two-photon width times the branching ratio into K K of 76 ± 6 ± 11 eV. A clear signal for the formation of the f J ( 1710) is observed and it is found to be dominated by the spin-two helicity-two state. No resonance is observed in the mass region around 2.2 GeV and an upper limit of 1.4 eV at 95% C.L. is derived for the two-photon width times the branching ratio into K 0 S K 0 S for the glueball candidate ξ (2230).

We report the result of a search for charginos and neutralinos, in e q e y collisions at 189 GeV centre-of-mass energy at LEP. No evidence for such particles is found in a data sample of 176 pb y1. Improved upper limits for these particles are set on the production cross sections. New exclusion contours in the parameter space of the Minimal Supersymmetric Standard Model are derived, as well as new lower limits on the masses of these supersymmetric particles. Under the assumptions of common gaugino and scalar masses at the GUT scale, we set an absolute lower limit on the mass of the lightest neutralino of 32.5 GeV, and a limit on the mass of the lightest chargino of 67.7 GeV for M-2 TeV.

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.

The production of c and b quarks γ γ collisions is studied with the L3 detector at LEP with 410 pb −1 of data, collected at centre-of-mass energies from 189 GeV to 202 GeV. Hadronic final states containing c and b quarks are identified by detecting electrons or muons from their semileptonic decays. The cross sections σ (e + e − → e + e − ccX) and σ (e + e − → e + e − bbX) are measured and compared to next-to-leading order perturbative QCD calculations. The cross section of b production is measured in γ γ collisions for the first time. It is in excess of the QCD prediction by a factor of three.