We search for anomalous ZZg and Zgg couplings with the L3 detector at LEP. The analysis is based on the study of the process e ' e ' TM Zg at center-of-mass energies in the range 161 GeV <'s < 183 GeV. No evidence for anomalous effects is found. Limits at the 95% confidence level are set on the values of the eight possible anomalous couplings. Depending on the type of coupling new physics scales below 213 GeV to 1083 GeV are excluded. © 1998 Elsevier Science B.V. All rights reserved.

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 F production are presented. In addition, two independent measurements of the ratio, f 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: Br(Z TM J + X) = (3.21 + 0.21 (stat.) J^1/ (sys.)) X 10 y 3, Br(Z TM F(1S) + X) < 4.4 X 10 y 5, fp = (7.1 + 2.1 (stat.) + 1.2(sys.) qjg (theo.)) X 10 y 2 . © 1999 Published by Elsevier Science B.V. All rights reserved. 1 Also supported by CONICET and Universidad Nacional de La Plata, CC 67, 1900 La Plata, Argentina. 2 Also supported by Panjab University, Chandigarh-160014, India. 3 Supported by Deutscher Akademischer Austauschdienst. 4 Also supported by the Hungarian OTKA fund under contract numbers T22238 and T026178. 5 Supported by the German Bundesministerium fur Bildung, Wissenschaft, Forschung und Technologie. 6 Supported by the National Natural Science Foundation of China. 7 Supported by the Hungarian OTKA fund under contract num­ bers T019181, F023259 and T024011. 8 Supported also by the Comisión Interministerial de Ciencia y Tecnología.

A search for unstable neutral and charged heavy leptons as well as for stable charged heavy leptons has been made at center-of-mass energies fi = 161 GeV and 6 = 172 GeV with the L3 detector at LEP. No evidence for their existence was found. We exclude unstable neutral leptons of Dirac (Majorana) type for masses below 78.0 (66.7), 78.0 (66.7) and 72.2 (58.2) GeV, if the heavy neutrino couples to the electron, muon or tau family, respectively. We exclude unstable charged heavy leptons for masses below 81.0 GeV for a wide mass range of the associated neutral heavy lepton. The production of stable charged heavy leptons with a mass less than 84.2 GeV is also excluded. If the unstable charged heavy lepton decays via mixing into a massless neutrino, we exclude masses below 78.7 GeV.

The inclusive semileptonic branching ratios b —► e u X , uX , r vX and vX have been measured at LEP with a Supported by the German Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie b Supported by the Hungarian OTKA fund under contract number T 14459 c Supported also by the Comisión Interministerial de Ciencia y Technologia d Also supported by CONICET and Universidad Nacional de La Plata, CC 67, 1900 La Plata, Argentina e Also supported by Panjab University, Chandigarh-160014, India the L3 detector. The analysis is based on 2-jet hadronic Z decays obtained in the data collected between 1991 and 1992. Three separate event samples are analysed, contain­ ing electrons, muons and large missing energy (neutrinos), respectively. From the electron sample, we measure Br(b —> ez/X) (10.89±0.20=b0.51)% and, from the muon sam­ ple, Br(b —► ¡jl vX ) = (10.82±0.15±0.59)%, where the first error is statistical and the second is systematic. From

A search for pair–produced charged Higgs bosons is performed with the L3 detector at LEP using data collected at a centre–of–mass energy of 188.6 GeV, corresponding to an integrated luminosity of 176.4 pb−1. Higgs decays into a charm and a strange quark or into a tau lepton and its associated neutrino are considered. The observed events are consistent with the expectations from Standard Model background processes. A lower limit of 65.5 GeV on the charged Higgs mass is derived at 95% confidence level, independent of the decay branching ratio Br(H± → τν). Submitted to Phys. Lett. B

Inclusive production of D * ± mesons in two-photon collisions was measured by the L3 experiment at LEP. The data were collected at a centre-of-mass energy Js = 189 GeV with an integrated luminosity of 176.4 pb 1 2345678. Differential cross sections of the process ee ^ee l)‘ X are determined as functions of the transverse momentum and pseudorapidity of the D* ± mesons in the kinematic region 1 GeV < p'/ < 5GeV and |t|d | < 1.4. The cross section integrated over this phase space domain is measured to be 132 + 22(stat.) + 26(syst.)pb. The differential cross sections are compared with next-to-leading order perturbative QCD calculations. © 1999 Published by Elsevier Science B.V. All rights reserved. 1 Also supported by CONICET and Universidad Nacional de La Plata, CC 67, 1900 La Plata, Argentina. 2 Also supported by Panjab University, Chandigarh-160014, India. 3 Deceased. 4 Also supported by the Hungarian OTKA fund under contract numbers T22238 and T026178. 5 Supported by the German Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie. 6 Supported by the National Natural Science Foundation of China. 7 Supported by the Hungarian OTKA fund under contract num­ bers T019181, F023259 and T024011. 8 Supported also by the Comisión Interministerial de Ciencia y Tecnología.

The variety of isotopes in cosmic rays allows us to study different aspects of the processes that cosmic rays undergo between the time they are produced and the time of their arrival in the heliosphere. In this paper we present measurements of the isotopic ratios 2H/4He, 3He/4He, 6Li/7Li, 7Be/(9Be+10Be) and 10B/11B in the range 0.2-1.4 GeV of kinetic energy per nucleon. The measurements are based on the data collected by the Alpha Magnetic Spectrometer, AMS-01, during the STS-91 flight in 1998 June.

Bose–Einstein correlations of pairs of identical charged pions produced in hadronic Z decays are analyzed in terms of various parametrizations. A good description is achieved using a Lévy stable distribution in conjunction with a model where a particle’s momentum is correlated with its space–time point of production, the τ-model. Using this description and the measured rapidity and transverse momentum distributions, the space–time evolution of particle emission in two-jet events is reconstructed. However, the elongation of the particle emission region previously observed is not accommodated in the τ-model, and this is investigated using an ad hoc modification.

We present results from a study of hadronic event structure in high energy e+e− interactions using the L3 detector at LEP. A new class of event shape distributions are measured at and above the Z boson pole for light quark (u, d, s, c) flavours. Energy flow correlations are studied for all hadronic events. Next-to-leading-log QCD calculations and QCD models with improved leading-log approximations are compared to data and good agreement is found at the Z-pole whereas some discrepancies are observed at higher centre-of-mass energies.

Measurement of the chemical and isotopic composition of cosmic rays is essential for the precise understanding of their propagation in the galaxy. While the model parameters are mainly determined using the B/C ratio, the study of extended sets of ratios can provide stronger constraints on the propagation models. In this paper, the relative abundances of light-nuclei lithium, beryllium, boron, and carbon are presented. The secondary-to-primary ratios Li/C, Be/C, and B/C have been measured in the kinetic energy range 0.35–45 GeV nucleon−1. The isotopic ratio 7Li/6Li is also determined in the magnetic rigidity interval 2.5–6.3 GV. The secondary-to-secondary ratios Li/Be, Li/B, and Be/B are also reported. These measurements are based on the data collected by the Alpha Magnetic Spectrometer AMS-01 during the STS-91 space shuttle flight in 1998 June. Our experimental results are in substantial agreement with other measurements, where they exist. We describe our light-nuclei data with a diffusive-reacceleration model. A 10%–15% overproduction of Be is found in the model predictions and can be attributed to uncertainties in the production cross-section data.

The (KSK +/-)-K-0 pi(-/+) final state in two-photon collisions is studied with the L3 detector at LEP at e(+)e(-) centre- of- mass energies from 183 to 209 GeV with an integrated luminosity of 664.6 pb(-1). The eta (1475) and f(1)(1420) mesons are observed and their contribution is separated by measuring the formation rates as a function of the photon virtuality Q(2). The eta(1475) is found to be dominant for Q(2) <= 0.01 GeV2 and its two- photon width is measured to be 0.23 +/- 0.05 (stat.) +/- 0.05 (sys.) keV. At higher Q(2), the f(1)(1420) is formed and decays to K*(892) K. The coupling and form factor parameters of this state are measured to be Gamma(gamma gamma) = 3.2 +/- 0.6 (stat.) +/- 0.7 ( sys.) keV and Lambda(1) = 926 +/- 72 (stat.) +/- 32 (sys.) MeV, respectively.

M.Aguilar,aa J.Alcaraz,aa J.Allaby,s B.Alpat,ae G.Ambrosi,t,ae H.Anderhub,ai L.Ao,g A.Arefiev,ad P.Azzarello,t E.Babucci,ae L.Baldini,j,l M.Basile,j D.Barancourt,u F.Barao,y,x G.Barbier,u G.Barreira,y R.Battiston,ae R.Becker,lU.Becker,l L.Bellagamba,j P.Béné,t J.Berdugo,aa P.Berges,l B.Bertucci,ae A.Biland,ai S.Bizzaglia,ae S.Blasko,ae G.Boella,ab M.Boschini,ab M.Bourquin,t L.Brocco,j G.Bruni,j M.Buénerd,u J.D.Burger,l W.J.Burger,ae X.D.Cai,l C.Camps,b P.Cannarsa,ai M.Capell,l D.Casadei,j J.Casaus,aa G.Castellini,q,j C.Cecchi,ae Y.H.Chang,m H.F.Chen,v H.S.Chen,i Z.G.Chen,g N.A.Chernoplekov,ac T.H.Chiueh,m K.Cho,p M.J.Choi,aƒ Y.Y.Choi,aƒ Y.L.Chuang,ag F.Cindolo,j V.Commichau,b A.Contin,j E.Cortina-Gil,t M.Cristinziani,t J.P.da Cunha,n T.S.Dai,l C.Delgado,aa J.D.Deus,x N.Dinu,ae,1 L.Djambazov,ai I.D’Antone,j Z.R.Dong,h P.Emonet,t J.Engelberg,w F.J.Eppling,l T.Eronen,ah G.Esposito,ae P.Extermann,t J.Favier,c E.Fiandrini,ae P.H.Fisher,l G.Fluegge,b N.Fouque,c Yu.Galaktionov,ad,l M.Gervasi,ab P.Giusti,j D.Grandi,ab O.Grimm,ai W.Q.Gu,h K.Hangarter,b A.Hasan,ai V.Hermel,c H.Hofer,ai M.A.Huang,ag W.Hungerford,ai M.Ionica,ae,1 R.Ionica,ae,1 M.Jongmanns,ai K.Karlamaa,w W.Karpinski,a G.Kenney,ai J.Kenny,ae D.H.Kim,p G.N.Kim,p K.S.Kim,aƒ M.Y.Kim,aƒ A.Klimentov,l,ad R.Kossakowski,c V.Koutsenko,l,ad M.Kraeber,ai G.Laborie,u T.Laitinen,ah G.Lamanna,ae E.Lanciotti,aa G.Laurenti,j A.Lebedev,l C.Lechanoine-Leluc,t M.W.Lee,p S.C.Lee,ag G.Levi,j P.Levtchenko,ae,2 C.L.Liu,z H.T.Liu,i I.Lopes,n G.Lu,g Y.S.Lu,i K.Lübelsmeyer,a D.Luckey,l W.Lustermann,ai C.Maña,aa A.Margotti,j F.Mayet,u R.R.McNeil,e B.Meillon,u M.Menichelli,ae A.Mihul,k A.Mourao,x A.Mujunen,w F.Palmonari,j A.Papi,ae H.B.Park,p W.H.Park,p M.Pauluzzi,ae F.Pauss,ai E.Perrin,t A.Pesci,j A.Pevsner,d M.Pimenta,y,x V.Plyaskin,ad V.Pojidaev,ad M.Pohl,t V.Postolache,ae,1 N.Produit,t P.G.Rancoita,ab D.Rapin,t F.Raupach,a D.Ren,ai Z.Ren,ag M.Ribordy,t J.P.Richeux,t E.Riihonen,ah J.Ritakari,w S.Ro,p U.Roeser,ai C.Rossin,u R.Sagdeev,o D.Santos,u G.Sartorelli,j C.Sbarra,j S.Schael,a A.Schultz von Dratzig,a G.Schwering,a G.Scolieri,ae E.S.Seo,o J.W.Shin,p E.Shoumilov,ad V.Shoutko,l R.Siedling,a D.Son,p T.Song,h M.Steuer,l G.S.Sun,h H.Suter,ai X.W.Tang,i Samuel C.C.Ting,l S.M.Ting,l M.Tornikoski,w J.Torsti,ah J.Trümper,r J.Ulbricht,ai S.Urpo,w E.Valtonen,ah J.Vandenhirtz,a F.Velcea,ae,1 E.Velikhov,ac B.Verlaat,ai,3 I.Vetlitsky,ad F.Vezzu,u J.P.Vialle,c G.Viertel,ai D.Vité,t H.Von Gunten,ai S.Waldmeier Wicki,ai W.Wallraff,a B.C.Wang,z J.Z.Wang,g Y.H.Wang,ag K.Wiik,w C.Williams,j S.X.Wu,l,m P.C.Xia,h J.L.Yan,g L.G.Yan,h C.G.Yang,i J.Yang,aƒ M.Yang,i S.W.Ye,v,4 P.Yeh,ag Z.Z.Xu,v H.Y.Zhang,ƒ Z.P.Zhang,v D.X.Zhao,h G.Y.Zhu,i W.Z.Zhu,g H.L.Zhuang,i A.Zichichi,j B.Zimmermann,ai P.Zuccon.ae

Measurements of inclusive production of the Lambda, Xi- and Xi*(1530) baryons in two-photon collisions with the L3 detector at LEP are presented. The inclusive differential cross sections for Lambda and Xi- are measured as a function of the baryon transverse momentum, pt, and pseudo-rapidity, eta. The mean number of Lambda, Xi- and Xi*(1530) baryons per hadronic two-photon event is determined in the kinematic range 0.4 GeV < pt< 2.5 GeV, |eta| < 1.2. Overall agreement with the theoretical models and Monte Carlo predictions is observed. A search for inclusive production of the pentaquark theta+(1540) in two-photon collisions through the decay theta+ -> proton K0s is also presented. No evidence for production of this state is found.

A measurement of the cosmic ray positron fraction e+/(e++e−) in the energy range of 1–30 GeV is presented. The measurement is based on data taken by the AMS-01 experiment during its 10 day Space Shuttle flight in June 1998. A proton background suppression on the order of 106 is reached by identifying converted bremsstrahlung photons emitted from positrons.

The reactions gamma gamma ->pi^+pi^-pi^+pi^- and gamma gamma ->pi^+pi^0pi^-pi^0 are studied with the L3 detector at LEP in a data sample collected at centre-of-mass energies from 161GeV to 209GeV with a total integrated luminosity of 698/pb. A spin-parity-helicity analysis of the rho^0 rho^0 and rho^+ rho^- systems for two-photon centre-of-mass energies between 1GeV and 3GeV shows the dominance of the spin-parity state 2+ with helicity 2. The contribution of 0+ and 0- spin-parity states is also observed, whereas contributions of 2- states and of a state with spin-parity 2+ and zero helicity are found to be negligible.

The reactions γγ→π+π−π+π− and γγ→π+π0π−π0 are studied with the L3 detector at LEP in a data sample collected at centre-of-mass energies from 161 GeV to 209 GeV with a total integrated luminosity of 698 pb−1. A spin-parity-helicity analysis of the ρ0ρ0 and ρ+ρ− systems for two-photon centre-of-mass energies between 1 and 3 GeV shows the dominance of the spin-parity state 2+ with helicity 2. The contribution of 0+ and 0− spin-parity states is also observed, whereas contributions of 2− states and of a state with spin-parity 2+ and zero helicity are found to be negligible.

The L3+C muon detector at the CERN electron-positron collider, LEP, is used for the detection of very-high-energy cosmic gamma-ray sources through the observation of muons of energies above 20, 30, 50 and 100 GeV. Daily or monthly excesses in the rate of single-muon events pointing to some particular direction in the sky are searched for. The periods from mid July to November 1999, and April to November 2000 are considered. Special attention is also given to a selection of known gamma-ray sources. No statistically significant excess is observed for any direction or any particular source. (c) 2006 Elsevier B.V. All rights reserved.