M. Biasini

High-temperature hydrolysis of FeCl3 in the presence of a surfactant gives monodisperse superparamagnetic colloidal nanocrystal clusters (CNCs) of magnetite with tunable sizes (30–180 nm; see scheme). The combination of superparamagnetism, high magnetization, and high water dispersibility makes these CNCs ideal candidates for applications such as drug delivery and bioseparation. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2007/z700197_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

The cross-section for e+e− → hadrons in the vicinity of the Z boson peak has been measured with the ALEPH detector at the CERN Large Electron Positron collider, LEP. Measurements of the Z mass, Mz = (91.174±0.070) GeV, the Z width Γz=(2.68±0.15) GeV, and of the peak hadronic cross-section, σhadpeak=(29.3±1.2) nb, are presented. With the constraints of the standard electroweak model, the number of light neutrino species is found to be Nv=3.27±0.30. this results rules out of the possibility of a fourth type of light neutrino at 98% CL.

Abstract A high‐temperature solution‐phase hydrolysis approach has been developed for the synthesis of colloidal magnetite nanocrystals with well‐controlled size and size distribution, high crystallinity, and high water solubility. The synthesis was accomplished by the hydrolysis and reduction of iron(III) cations in diethylene glycol with a rapidly injected solution of sodium hydroxide at an elevated temperature. The high reaction temperature allows for control over size and size distribution and yields highly crystalline products. The superior water solubility is achieved by using a polyelectrolyte, that is, poly(acrylic acid) as the capping agent, the carboxylate groups of which partially bind to the nanocrystal surface and partially extend into the surrounding water. The direct synthesis of water‐soluble nanocrystals eliminates the need for additional surface modification steps which are usually required for treating hydrophobic nanocrystals produced in nonpolar solvents through the widely recognized pyrolysis route. The abundant carboxylate groups on the nanocrystal surface allow further modifications, such as bioconjugation, as demonstrated by linking cysteamine to the particle surface. The monodisperse, highly water‐soluble, superparamagnetic, and biocompatible magnetite nanocrystals should find immediate important biomedical applications.

The design and construction of the silicon strip microvertex detector (SMD) of the L3 experiment at LEP are described. We present the sensors, readout electronics, data acquisition system, mechanical assembly and support, displacement monitoring systems and radiation monitoring system of the recently installed double-sided, double-layered SMD. This detector utilizes novel and sophisticated techniques for its readout.

A search for exotic unstable neutral and charged heavy leptons as well as for stable charged heavy leptons is performed with the L3 detector at LEP. Sequential, vector and mirror natures of heavy leptons are considered. No evidence for their existence is found and lower limits on their masses are set.

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 and 209 GeV. The cross sections of the process e+e−→νν̄γ(γ) 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 Nν=2.98±0.05±0.04. 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 models. No evidence for such models is found. Among others, lower limits between 1.5 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 6.

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, αs, from hadronic event shapes and the study of effects of soft gluon coherence in charged particle multiplicity and momentum distributions.

The absolute muon flux between 20 GeV and 3000 GeV is measured with the L3 magnetic muon spectrometer for zenith angles ranging from 0 degree to 58 degree. Due to the large exposure of about 150 m2 sr d, and the excellent momentum resolution of the L3 muon chambers, a precision of 2.3 % at 150 GeV in the vertical direction is achieved. The ratio of positive to negative muons is studied between 20 GeV and 500 GeV, and the average vertical muon charge ratio is found to be 1.285 +- 0.003 (stat.) +- 0.019 (syst.).

Scalar partners of quarks and leptons, predicted in supersymmetric models, are searched for in e^+e^- collisions at centre-of-mass energies between 192GeV and 209GeV at LEP. No evidence for any such particle is found in a data sample of 450 pb^-1. Upper limits on their production cross sections are set and lower limits on their masses are derived in the framework of the Minimal Supersymmetric Standard Model.

We search for neutral heavy leptons that are isosinglets under the standard SU (2)L gauge group. Such neutral heavy leptons are expected in many extensions of the standard model. Three types of heavy leptons Ne, Nμ, Nτ associated with the three neutrino types ve, vμ, vτ have been directly searched for and no evidence for a signal has been found. We set the limit Br(NSu0 → vℓNℓ) < 3 x 10−5 at the 95% CL for mass range from 3 GeV up to Mz.

Angewandte ChemieVolume 119, Issue 23 p. 4420-4423 Zuschrift Superparamagnetic Magnetite Colloidal Nanocrystal Clusters† Jianping Ge Dr., Jianping Ge Dr. Department of Chemistry, University of California, Riverside, CA 92521, USA, Fax: (+1) 951-827-4713Search for more papers by this authorYongxing Hu, Yongxing Hu Department of Chemistry, University of California, Riverside, CA 92521, USA, Fax: (+1) 951-827-4713Search for more papers by this authorMaurizio Biasini Dr., Maurizio Biasini Dr. Department of Physics and Astronomy, University of California, Riverside, CA 92521, USASearch for more papers by this authorWard P. Beyermann Prof., Ward P. Beyermann Prof. Department of Physics and Astronomy, University of California, Riverside, CA 92521, USASearch for more papers by this authorYadong Yin Prof., Yadong Yin Prof. yadong.yin@ucr.edu Department of Chemistry, University of California, Riverside, CA 92521, USA, Fax: (+1) 951-827-4713Search for more papers by this author Jianping Ge Dr., Jianping Ge Dr. Department of Chemistry, University of California, Riverside, CA 92521, USA, Fax: (+1) 951-827-4713Search for more papers by this authorYongxing Hu, Yongxing Hu Department of Chemistry, University of California, Riverside, CA 92521, USA, Fax: (+1) 951-827-4713Search for more papers by this authorMaurizio Biasini Dr., Maurizio Biasini Dr. Department of Physics and Astronomy, University of California, Riverside, CA 92521, USASearch for more papers by this authorWard P. Beyermann Prof., Ward P. Beyermann Prof. Department of Physics and Astronomy, University of California, Riverside, CA 92521, USASearch for more papers by this authorYadong Yin Prof., Yadong Yin Prof. yadong.yin@ucr.edu Department of Chemistry, University of California, Riverside, CA 92521, USA, Fax: (+1) 951-827-4713Search for more papers by this author First published: 24 May 2007 https://doi.org/10.1002/ange.200700197Citations: 78 † Y.Y. thanks the University of California, Riverside for startup funds. We thank Dr. J. Guo and Dr. C. Dong at the Lawrence Berkeley National Laboratory for help with the XAS analyses, and Dr. K. N. Bozhilov and Mr. S. McDaniel at the Central Facility for Advanced Microscopy and Microanalysis at UCR for assistance with the TEM measurements. Read the full textAboutPDF ToolsRequest permissionAdd to favorites ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract Magnetit in Form monodisperser superparamagnetischer kolloidaler Nanokristallcluster (CNCs; 30–180 nm groß) entsteht bei der Hydrolyse von FeCl3 bei hoher Temperatur und in Gegenwart eines Tensids (siehe Schema). Die Kombination aus Superparamagnetismus, hoher Magnetisierung und guter Dispergierbarkeit in Wasser empfiehlt diese CNCs für Anwendungen wie Wirkstofftransport und die Trennung biologischer Verbindungen. Citing Literature Supporting Information Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2001/2007/z700197_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. Volume119, Issue23June 4, 2007Pages 4420-4423 This is the German version of Angewandte Chemie. Note for articles published since 1962: Do not cite this version alone. Take me to the International Edition version with citable page numbers, DOI, and citation export. We apologize for the inconvenience. RelatedInformation

Solvothermal reaction of a mixture of Sn, Mn, and Te at 200 degrees C using teta as the solvent yields a novel inorganic-organic hybrid solid [Mn(teta)(en)].[Mn(teta)][Mn(SnTe4)2.Mn(teta)] (teta=triethylenetetramine and en=ethylenediamine; 1), which has a homochiral single-stranded helical structure. The material is a semiconductor with a band gap of 0.88 eV and shows paramagnetic behavior between 2 and 300 K.

The formation of the η′ in the reaction e+e−→e+e−η′→e+e−π+π−γ has been measured by the L3 detector at a centre-of-mass energy of 91GeV. The radiative width of the η′ has been found to be Γγγ=4.17±0.10(stat.)±0.27(sys.)keV. The Q2 dependence of the η′ formation cross section has been measured for Q2≤10GeV2 and the η′ electromagnetic transition form factor has been determined. The form factor can be parametrised by a pole form with Λ=0.900±0.046(stat.)±0.022(sys.)GeV. It is also consistent with recent non-perturbative QCD calculations.

The structure of hadronic events fromZ 0 decay is studied by measuring event shape variables, factorial moments, and the energy flow distribution. The distributions, after correction for detector effects and initial and final state radiation, are compared with the predictions of different QCD Monte Carlo programs with optimized parameter values. These Monte Carlo programs use either the second order matrix element or the parton shower evolution for the perturbative QCD calculations and use the string, the cluster, or the independent fragmentation model for hadronization. Both parton shower andO(α 2 s matrix element based models with string fragmentation describe the data well. The predictions of the model based on parton shower and cluster fragmentation are also in good agreement with the data. The model with independent fragmentation gives a poor description of the energy flow distribution. The predicted energy evolutions for the mean values of thrust, sphericity, aplanarity, and charge multiplicity are compared with the data measured at different center-of-mass energies. The parton shower based models with string or cluster fragmentation are found to describe the energy dependences well while the model based on theO(α 2 s calculation fails to reproduce the energy dependences of these mean values.

Single top production in e+e- annihilations is searched for in data collected by the L3 detector at centre-of-mass energies from 189 to 209 GeV, corresponding to a total integrated luminosity of 634 pb-1. Investigating hadronic and semileptonic top decays, no evidence of single top production at LEP is obtained and upper limits on the single top cross section as a function of the centre-of-mass energy are derived. Limits on possible anomalous couplings, as well as on the scale of contact interactions responsible for single top production are determined.

We present a study of the global event shape variables thrust and heavy jet mass, of energy-energy correlations and of jet multiplicities based on 250 000 hadronic Z0 decays. The data are compared to new QCD calculations including resummation of leading and next-to-leading logarithms to all orders. We determine the strong coupling constant αs (91.2 GeV) = 0.125±0.003 (exp) ± 0.008 (theor). The first error is the experimental uncertainty. The second error is due to hadronization uncertainties and approximations in the calculations of the higher order corrections.

In a search for the Standard Model Higgs boson, carried out on 212.5 pb-1 of data collected by the L3 detector at the highest LEP centre-of-mass energies, including 116.5 pb-1 above root(s) = 206GeV, an excess of candidates for the process e+e- -> Z* -> HZ is found for Higgs masses near 114.5GeV. We present an analysis of our data and the characteristics of our strongest candidates.

We report on a search for the first generation heavy neutrino that is an isosinglet under the standard SU(2)_L gauge group. The data collected with the L3 detector at center-of-mass energies between 130 GeV and 208 GeV are used.The decay channel N_e --> eW is investigated and no evidence is found for a heavy neutrino, N_e, in a mass range between 80 GeV and 205 GeV. Upper limits on the mixing parameter between the heavy and light neutrino are derived.

We analyse e+e−→ττγ events using 100pb−1 of data collected by the L3 experiment during the 1991-1995 LEP runs at the Z pole. From the energy of the photons and their isolation from the tau decay products, we determine the anomalous magnetic and electric dipole moments of the tau to be, respectively: aτ=0.004±0.027±0.023;dτ=(0.0±1.5±1.3)×10−16e·cm.This is a direct measurement of these τ form factors at q2=0.

We present the first measurement of the left-right cross section asymmetry (${\mathit{A}}_{\mathit{L}\mathit{R}}$) for Z boson production by ${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ collisions. The measurement was performed at a center-of-mass energy of 91.55 GeV with the SLD detector at the SLAC Linear Collider which utilized a longitudinally polarized electron beam. The average beam polarization was (22.4\ifmmode\pm\else\textpm\fi{}0.6)%. Using a sample of 10 224 Z decays, we measure ${\mathit{A}}_{\mathit{L}\mathit{R}}$ to be 0.100\ifmmode\pm\else\textpm\fi{}0.044(stat)\ifmmode\pm\else\textpm\fi{}0.004(syst), which determines the effective weak mixing angle to be ${\mathrm{sin}}^{2}$${\mathrm{\ensuremath{\theta}}}_{\mathit{W}}^{\mathit{e}\mathit{f}\mathit{f}}$=0.2378 \ifmmode\pm\else\textpm\fi{}0.0056(stat)\ifmmode\pm\else\textpm\fi{}0.0005(syst).

Doubly-charged Higgs bosons are searched for in e^+e^- collision data collected with the L3 detector at LEP at centre-of-mass energies up to 209 GeV. Final states with four leptons are analysed to tag the pair-production of doubly charged Higgs bosons. No significant excess is found and lower limits at 95% confidence level on the doubly-charged Higgs boson mass are derived. They vary from 95.5 GeV to 100.2 GeV, depending on the decay mode. Doubly-charged Higgs bosons which couple to electrons would modify the cross section and forward-backward asymmetry of the e^+e^- -> e^+e^- process. The measurements of these quantities do not deviate from the Standard Model expectations and doubly-charged Higgs bosons with masses up to the order of a TeV are excluded.

The ηπ+π− final state in two-photon collisions is studied with the L3 detector at LEP, at centre-of-mass energies from 183 to 209 GeV with an integrated luminosity of 664.6 pb−1. The f1(1285) meson is observed and the Q2 dependence of its production is compared to different form factor models. The γγ-coupling parameter Γγγ is found to be 3.5±0.6(stat.)±0.5(sys.) keV. The branching fraction Γ(f1(1285)→a0π)/Γ(f1(1285)→ηππ) is also measured.

Well-above room temperature and electron concentration dependent ferromagnetism was observed in n-type ZnO:Mn films, indicating long-range ferromagnetic order. Magnetic anisotropy was also observed in these ZnO:Mn films, which is another indication for intrinsic ferromagnetism. The electron-mediated ferromagnetism in n-type ZnO:Mn contradicts the existing theory that the magnetic exchange in ZnO:Mn materials is mediated by holes.

Using a data sample of 1 475 000 Z → qq̄(γ) events collected during 1994 with the L3 detector at LEP, we have studied the purely leptonic decays of heavy flavour mesons, Ds− → τ−ντ and B− → τ−ντ. A signal is observed in the invariant mass distribution M(γDs−) corresponding to the decay sequence D∗− → γDs−, Ds− → τ−ντ, τ− → l−νlντ. The branching fraction for Ds− → τ−ντ decays is measured to be β(Ds− → τ−ντ) = 0.074 ± 0.028(stat) ± 0.016(syst) ± 0.018(norm). No signal of B− → τ−ντ decays is observed in the data, corresponding to an upper limit on the branching franction β(B− → τ−ντ) < 5.7 × 10−4 at 90% CL.

The measurements of hadron and lepton-pair production cross sections and leptonic forward–backward asymmetries performed with the L3 detector at centre-of-mass energies between 130 GeV and 189 GeV are used to search for new physics phenomena such as: contact interactions, exchange of virtual leptoquarks, scalar quarks and scalar neutrinos, effects of TeV strings in models of quantum gravity with large extra dimensions and non-zero sizes of the fermions. No evidence for these phenomena is found and new limits on their parameters are set.

We report the result of a search for charginos and neutralinos, in e+e− collisions at 189 GeV centre-of-mass energy at LEP. No evidence for such particles is found in a data sample of 176 pb−1. 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 M2<2TeV.

We present a study of the inclusive production of π0, η, Ks0 and Λ based on 929,000 hadronic Z decays recorded with the L3 detector at LEP. The measured inclusive momentum distributions have been compared with predictions from parton shower models as well as an analytical Quantum Chromodynamics calculation. Comparing to low energy e+e- data, we find that QCD describes the energy evolution of the hadron spectrum.

We report on the measurement of the leptonic and hadronic cross sections and leptonic forward-backward asymmetries at theZ peak with the L3 detector at LEP. The total luminosity of 40.8 pb−1 collected in the years 1990, 1991 and 1992 corresponds to 1.09·106 hadronic and 0.98·105 leptonicZ decays observed. These data allow us to determine the electroweak parameters. From the cross sections we derive the properties of theZ boson: $$\begin{gathered} M_Z = 91195 \pm 9MeV\Gamma _{\rm Z} = 2494 \pm 10MeV \hfill \\ \Gamma _{had} = 1748 \pm 10MeV\Gamma _\ell = 83.49 \pm 0.46MeV \hfill \\ \end{gathered} $$ assuming lepton universality. We obtain an invisible width of Γinv=496.5±7.9 MeV which, in the Standard Model, corresponds to a number of light neutrino species ofN v=2.981±0.050. Using also the three leptonic forward-backward asymmetries and the average tau polarization, we determine the effective vector and axial-vector coupling constants of the neutral weak current to charged leptons to be: $$\bar g^\ell v = - 0.0378_{ - 0.0042}^{ + 0.0045} \bar g^\ell _A = - 0.4998 \pm 0.0014.$$ Within the framework of the Standard Model, and including our measurements of the $$Z \to b\bar b$$ forward-backward asymmetry and partial decay width, we derive an effective electroweak mixing angle of $$sin^2 \bar \theta _W = 0.2326 \pm 0.0012$$ . We obtain an estimate for the strong coupling constant, αS=0.142 ± 0.013 and for the top-quark mass,m t =158 −40 +32 ±19(Higgs) GeV, where the second error arises due to the uncertainty in the Higgs-boson mass.

The results of the searches for neutral Higgs boson production in the process e+e− → Z∗ H0 are reported, focusing on Higgs boson masses below 70 GeV. The data sample consists of three million hadronic Z0 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− → Z∗h0 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.

Interventional radiologists and staff members, during all their professional activities, are frequently exposed to protracted and fractionated low doses of ionizing radiation. Due to skin tissues and peripheral blood irradiation, these exposures can result in deterministic effects (radiodermatitis, aged skin, and hand depilation) or stochastic ones (skin and non-solid cancer incidence). The authors present a novel approach to perform online monitoring of the staff during their interventions by using a device based on an Active Pixel Sensor. The performance of the sensor as an X-ray radiation detector has been evaluated with a proper experimental setup: the number of photons and the generated charge have been assessed as dosimetric observables from the frames acquired by the sensor using a two-threshold clustering algorithm, the efficiency of which has been evaluated as well. The correlation of these observables with passive dosimeter dose measurements has been analyzed: a good linearity has been demonstrated, and the response difference between pulsed and continuous operational modes is reduced to less than 10%, marking a distinct improvement with respect to commercial Active Personal Dosimeters.

We report measurements of sin2β and cos2β using a time-dependent Dalitz plot analysis of B0→D(*)h0 with D→KS0π+π− decays, where the light unflavored and neutral hadron h0 is a π0, η, or ω meson. The analysis uses a combination of the final data sets of the BaBar and Belle experiments containing 471×106 and 772×106 BB¯ pairs collected at the ϒ(4S) resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. We measure sin2β=0.80±0.14(stat)±0.06(syst)±0.03(model) and cos2β=0.91±0.22(stat)±0.09(syst)±0.07(model). The result for the direct measurement of the angle is β=(22.5±4.4(stat)±1.2(syst)±0.6(model))°. The last quoted uncertainties are due to the composition of the D0→KS0π+π− decay amplitude model, which is newly established by a Dalitz plot amplitude analysis of a high-statistics e+e−→cc¯ data sample as part of this analysis. We find the first evidence for cos2β>0 at the level of 3.7 standard deviations. The measurement excludes the trigonometric multifold solution π/2−β=(68.1±0.7)° at the level of 7.3 standard deviations and therefore resolves an ambiguity in the determination of the apex of the CKM Unitarity Triangle. The hypothesis of β=0° is ruled out at the level of 5.1 standard deviations, and thus CP violation is observed in B0→D(*)h0 decays. The measurement assumes no direct CP violation in B0→D(*)h0 decays.3 MoreReceived 17 April 2018DOI:https://doi.org/10.1103/PhysRevD.98.112012Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)PropertiesCP violationParticles & Fields

Recent theories propose that quantum gravity effects may be observable at LEP energies via gravitons that couple to Standard Model particles and propagate into extra spatial dimensions. The associated production of a graviton and a photon is searched for as well as the effects of virtual graviton exchange in the processes: e+e- -> gamma gamma, ZZ, WW, mu mu, tau tau, qq and ee No evidence for this new interaction is found in the data sample collected by the L3 detector at LEP at centre-of-mass energies up to 183 GeV. Limits close to 1 TeV on the scale of this new scenario of quantum gravity are set.

The hadronic photon structure function Fγ2 is studied in the reaction e+e−→e+e−hadrons at LEP with the L3 detector. The data, collected from 1991 to 1995 at a centre-of-mass energy s≃91 GeV, correspond to an integrated luminosity of 140 pb−1. The photon structure function Fγ2 is measured in the Q2 interval 1.2 GeV2 ≤Q2≤9.0 GeV2 and the x interval 0.002<x<0.2. Fγ2 shows a linear growth with lnQ2. The value of the slope α−1dFγ2(Q2)/dlnQ2 is measured to be 0.079±0.011±0.009.

The production of c and b quarks in gamma-gamma 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 sigma(e+e- -> e+e- c c~ X) and sigma(e+e- -> e+e- b b~ X) are measured and compared to next-to-leading order perturbative QCD calculations. The cross section of b production is measured in gamma-gamma collisions for the first time. It is in excess of the QCD prediction by a factor of three.

Final results of the search for the Standard Model Higgs boson are presented for the data collected by the L3 detector at LEP at centre-of-mass energies up to about 209 GeV. These data are compared with the expectations of Standard Model processes for Higgs boson masses up to 120 GeV. A lower limit on the mass of the Standard Model Higgs boson of 112.0 GeV is set at the 95 % confidence level. The most significant high mass candidate is a Hnunu event. It has a reconstructed Higgs mass of 115 GeV and it was recorded at root(s)=206.4 GeV.

We have searched for neutralinos produced via the reactions e+e− → χχ′ and e+e−→ χ′χ′, where the next-to lightest neutralino, χ′, decays into the lightest neutralino, χ, and either a photon or a fermion pair. Based on 1.8 × 106 hadronic Z decays collected with the L3 detector at LEP, no signal has been observed. We present upper limits of a few times 10−5 on the branching ratios Z → χχ′ and Z → χ′χ′. In the framework of the Minimial Supersymmetric Standard Model, we exclude a lightest χ with mχ less than 18 GeV, if either tan β > 2 or the gluino mass m≈g > 100 GeV.

The e+e−→e+e−KS0K±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 K0SK±π∓ final state shows an enhancement around 1470 MeV, which is identified with the pseudoscalar meson η(1440). This state is observed in γγ collisions for the first time and its two-photon width is measured to be Γγγ(η(1440))×BR(η(1440)→KK̄π)=212±50 (stat.)±23 (sys.) eV. Clear evidence is also obtained for the formation of the axial vector mesons f1(1420) and f1(1285). In the ηπ+π− channel the f1(1285) is observed, and upper limits for the formation of η(1440) and η(1295) are obtained.

A search for pair-produced charged Higgs bosons is performed with the L3 detector at LEP using data collected at centre-of-mass energies between 189 and 209GeV, corresponding to an integrated luminosity of 629.4/pb. Decays into a charm and a strange quark or into a tau lepton and its neutrino are considered. No significant excess is observed and lower limits on the mass of the charged Higgs boson are derived at the 95% confidence level. They vary from 76.5 to 82.7GeV, as a function of the H->tv branching ratio.

We present a study of the structure of hadronic events recorded by the L3 detector at center-of-mass energies of 130 and 136 GeV. The data sample corresponds to an integrated luminosity of 5 pb−1 collected during the high energy run of 1995. The shapes of the event shape distributions and the energy dependence of their mean values are well reproduced by QCD models. From a comparison of the data with resummed O(αs2) QCD calculations, we determine the strong coupling constant to be αs(133 GeV) = 0.107 ± 0.005(exp) ± 0.006(theor).

A three-dimensional mapping of the Fermi surface (FS) of the heavy-fermion antiferromagnetic system ${\mathrm{CeIn}}_{3}$ in the paramagnetic phase was determined via measurements of the angular correlation of the electron-positron annihilation radiation for five crystal orientations. The two equivolume FS sheets observed agree with the predictions of our band-structure calculations regarding the Ce $4f$ electrons as fully localized. Moreover, a comparison of our results with the de Haas--van Alphen signals observed in the antiferromagnetic phase suggests that the f electrons retain the local atomic character in the magnetically ordered phase.

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 L\'evy stable distribution in conjunction with a model where a particle's momentum is correlated with its space-time point of production, the \taumodel. 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 \taumodel, and this is investigated using an \adhoc/ modification.

Extra spatial dimensions are proposed by recent theories that postulate the scale of gravity to be of the same order as the electroweak scale. A sizeable interaction between gravitons and Standard Model particles is then predicted. Effects of these new interactions in boson and fermion pair production are searched for in the data sample collected at centre-of-mass energies above the Z pole by the L3 detector at LEP. In addition, the direct production of a graviton associated with a Z boson is investigated. No statistically significant hints for the existence of these effects are found and lower limits in excess of 1 TeV are derived on the scale of this new theory of gravity.

The K0s K0s 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 Kbar 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 K0s K0s for the glueball candidate xi(2230).

The reaction e+e− → e+e−γ∗γ∗ → e+e− hadrons is analysed using data collected by the L3 detector during the LEP runs at s = 130−140 GeV and s = 161 GeV. The cross sections σ(e+e− → e+e− hadrons) and σ(γγ → hadrons) are measured in the interval 5 ≤ Wγγ ≤ 75 GeV. The energy dependence of the σ(γγ → hadrons) cross section is consistent with the universal Regge behaviour of total hadronic cross sections.

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^{-1} of integrated luminosity. The cross section of the process e+e- -> nu nu gamma (gamma) is measured and the number of light neutrino flavours is determined to be N_\nu = 3.011 +/- 0.077 including lower 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.

Measurements of the two-photon interaction e+e− → e+e− + hadrons at s≃ 91GeV and s≃ 183GeV are presented. The double-tag events, collected with the L3 detector, correspond to interated luminosities of 140 pb−1 at 91 GeV and 52 pb−1 at 183 GeV. The cross-section of γ∗γ∗ collisions has been measured at 〈Q2〉 = 3.5 GeV2 and 〈Q2〉 = 14 GeV2. The data agree well with predictions based on perturbative QCD, while the Quark Parton Model alone is insufficient to describe the data.

The cross section of W-boson pair-production is measured with the L3 detector at LEP. In a data sample corresponding to a total luminosity of 629.4 pb−1, collected at centre-of-mass energies ranging from 189 to 209 GeV, 9834 four-fermion events with W bosons decaying into hadrons or leptons are selected. The total cross section is measured with a precision of 1.4% and agrees with the Standard Model expectation. Assuming charged-lepton universality, the branching fraction for hadronic W-boson decays is measured to be: Br(W→hadrons)=67.50±0.42(stat.)±0.30(syst.)%, in agreement with the Standard Model. Differential cross sections as a function of the W− production angle are also measured for the semi-leptonic channels qqeν and qqμν.

A search, in e^+e^- collisions, for chargino, neutralino, scalar lepton and scalar quark pair-production is performed, without assuming R-parity conservation in decays, in the case that only one of the coupling constants lambda_ijk or lambda''_ijk is non-negligible. No signal is found in data up to a centre-of-mass energy of 208GeV. Limits on the production cross sections and on the masses of supersymmetric particles are derived.

From the analysis of the reactions e+e−→l+l−(nγ) (l=e,μ,τ) we observe four events, one e+e−γγ and three μ+μ−γγ, with the invariant mass of the photon pairs close to 60 GeV. These events were selected from a data sample collected in the L3 detector corresponding to 950 000 produced Z0's. More data are necessary to ascertain the origin of these events.

We have searched for lepton flavour violation in Z boson decays into lepton pairs using all data collected with the L3 detector during the 1990, 1991 and 1992 runs on an event sample corresponding to 1 500 000 Z's produced. At the 95% confidence level the upper limits on the branching ratio for Z→eμ is 0.6×10−5 and for Z→μτ this is 1.9×10−5.

We search, in the context of extra-dimension scenarios, for the possible existence of brane fluctuations, called branons. Events with a single photon or a single Z-boson and missing energy and momentum collected with the L3 detector in e^+ e^- collisions at centre-of-mass energies sqrt{s}=189-209$ GeV are analysed. No excess over the Standard Model expectations is found and a lower limit at 95% confidence level of 103 GeV is derived for the mass of branons, for a scenario with small brane tensions. Alternatively, under the assumption of a light branon, brane tensions below 180 GeV are excluded.

We report a measurement of Rb= ΓbbΓhad from Z→qq events at LEP. Z→bb events are identified using a multidimensional analysis based on a neural network approach. We obtain 60% sample purity with an efficiency of 35%. Our measured value of Rb is 0.222±0.003±0.007.

The process e+e−→W+W−γ is studied using the data collected by the L3 detector at LEP. New results, corresponding to an integrated luminosity of 427.4 pb−1 at centre-of-mass energies from 192 to 207 GeV, are presented. The W+W−γ cross sections are measured to be in agreement with Standard Model expectations. No hints of anomalous quartic gauge boson couplings are observed. Limits at 95% confidence level are derived using also the process e+e−→νν̄γγ.

The evolution of the electromagnetic coupling, alpha, in the momentum-transfer range 1800GeV^2 < -Q^2 < 21600GeV^2 is studied with about 40000 Bhabha-scattering events collected with the L3 detector at LEP at centre-of-mass energies 189-209GeV. The running of alpha is parametrised as: alpha(Q^2) = alpha_0/(1-C Delta alpha(Q^2)), where alpha_0=\alpha(Q^2=0) is the fine-structure constant and C=1 corresponds to the evolution expected in QED. A fit to the differential cross section of the e+e- ->e+e- process for scattering angles in the range |cos theta|<0.9 excludes the hypothesis of a constant value of alpha, C=0, and validates the QED prediction with the result: C = 1.05 +/- 0.07 +/- 0.14, where the first uncertainty is statistical and the second systematic.

Diluted magnetic semiconducting ZnO:Co thin films with above room-temperature TC were prepared. Transmission electron microscopy and x-ray diffraction studies indicate the ZnO:Co thin films are free of secondary phases. The magnetization of the ZnO:Co thin films shows a free electron carrier concentration dependence, which increases dramatically when the free electron carrier concentration exceeds ∼1019 cm−3, indicating a carrier-mediated mechanism for ferromagnetism. The anomalous Hall effect is observed in the ZnO:Co thin films. The anomalous Hall coefficient and its dependence on longitudinal resistivity were analyzed. The presence of a side-jump contribution further supports an intrinsic origin for ferromagnetism in ZnO:Co thin films. These observations together with the magnetic anisotropy and magnetoresistance results support an intrinsic carrier-mediated mechanism for ferromagnetic exchange in ZnO:Co diluted magnetic semiconductor materials.

The reaction e+e−→e+e−γ∗γ∗→e+e−hadrons for quasi-real photons is studied using data from s=183 GeV up to 202 GeV. Results on the total cross sections σ(e+e−→e+e−hadrons) and σ(γγ→hadrons) are given for the two-photon centre-of-mass energies 5 GeV⩽Wγγ⩽185 GeV. The total cross section of two real photons is described by a Regge parametrisation. We observe a steeper rise with the two-photon centre-of-mass energy as compared to the hadron–hadron and the photon–proton cross sections. The data are also compared to the expectations of different theoretical models.

We report on the measurement of W-boson pair-production with the L3 detector at LEP at a centre-of-mass energy of 161.34 GeV. In a data sample corresponding to a total luminosity of 11 pb−1, we select four-fermion events with high invariant masses of pairs of hadronic jets or leptons. Combining all final states, the measured total cross section for W-pair production is: sigmaWW = 2.89−0.70+0.81(stat.) ± 0.14 (syst.) pb. Within the Standard Model, this corresponds to a mass of the W boson of: MW = 80.80−0.42+0.48 (exp.) ± 0.03 (LEP) GeV. Limits on anomalous triple-vector-boson couplings are derived.

A search for the Standard Model Higgs boson has been performed with the L3 detector at LEP. The data sample was collected at three centre-of-mass energies, 161.3, 170.3 and 172.3 GeV with integrated luminosities of 10.8, 1.0 and 9.2 pb, respectively. No Higgs signal is observed. In combination with previous data taken at the Z resonance, a lower Higgs mass limit, MH > 69.5 GeV, is obtained at 95% confidence level.

We measure Bose-Einstein correlations between like-sign charged pion pairs in hadronic Z decays with the L3 detector at LEP. The analysis is performed in three dimensions in the longitudinal center-of-mass system. The pion source is found to be elongated along the thrust axis with a ratio of transverse to longitudinal radius of $0.81\pm 0.02 ^{+0.03}_{-0.19}$.

The search for an additional heavy gauge boson Z′ is described. The models considered are based on either a superstring-motivated E6 or on a left-right symmetry and assume a minimal Higgs sector. Cross sections and asymmetries measured with the L3 detector in the vicinity of the Z resonance during the 1990 and 1991 running periods are used to determine limits on the Z-Z′ gauge boson mixing angle and on the Z′ mass. For Z′ masses above the direct limits, we obtain the following allowed ranges of the mixing angle, θM at the 95% confidence level: −0.004 ⪕ θM⪕ 0.015 for the χ model, −0.003 ⪕ θM⪕ 0.020 for the ψ model, −0.029 ⪕ θM⪕ 0.010 for the η model, −0.002 ⪕ θM⪕ 0.020 for the LR model,

Total and differential cross sections for the process e+e− → γγ(γ), and the total cross section for the process e+e− → γγγ, are measured at energies around 91 GeV using the data collected with the L3 detector from 1991 to 1993. We set lower limits, at 95% CL, on a contact interaction energy scale parameter Λ > 602 GeV, on the mass of an excited electron me∗>146GeV and on the QED cut-off parameters Λ+ > 149 GeV and Λ_ > 143 GeV. Upper limits are also set o branching fractions of Z decaying into γγ, π° and ηγ of 5.2 × 10−5, 5.2 × 10−5 and 7.6 × 10−5 respectively. The reactions e+e− → ℓ+ℓ−nγ (ℓ = e, μ, τ) are studied using the data collected from 1990 to 1994. The data are consistent with the QED expectations.

A measurement of the inclusive charmless semileptonic branching fraction of beauty hadrons, b→Xuℓν, has been performed using almost two million hadronic Z decays collected by the L3 experiment at LEP, yielding the result: Br(b→Xuℓν)=(3.3±1.0±1.7)×10−3. The first uncertainty is statistical and the second is systematic. The modulus of the Cabibbo-Kobayashi-Maskawa matrix element Vub extracted from this measurement is: |Vub|=(6.0+0.8−1.0+1.4−1.9±0.2)×10−3, where the uncertainties are statistical, systematic and theoretical, respectively.

Results are presented from a study of the structure of high energy hadronic events recorded by the L3 detector at sqrt(s)>192 GeV. The distributions of several event shape variables are compared to resummed O(alphaS^2) QCD calculations. We determine the strong coupling constant at three average centre-of-mass energies: 194.4, 200.2 and 206.2 GeV. These measurements, combined with previous L3 measurements at lower energies, demonstrate the running of alphaS as expected in QCD and yield alphaS(mZ) = 0.1227 +- 0.0012 +- 0.0058, where the first uncertainty is experimental and the second is theoretical.

Anomalous couplings of the Higgs boson are searched for through the processes e^+ e^- -> H gamma, e^+ e^- -> e^+ e^- H and e^+ e^- -> HZ. The mass range 70 GeV < m_H < 190 GeV is explored using 602 pb^-1 of integrated luminosity collected with the L3 detector at LEP at centre-of-mass energies sqrt(s)=189-209 GeV. The Higgs decay channels H -> ffbar, H -> gamma gamma, H -> Z\gamma and H -> WW^(*) are considered and no evidence is found for anomalous Higgs production or decay. Limits on the anomalous couplings d, db, Delta(g1z), Delta(kappa_gamma) and xi^2 are derived as well as limits on the H -> gamma gamma and H -> Z gamma decay rates.

A three-dimensional mapping of the Fermi surface (FS) of the rare-earth compound ${\mathrm{ErGa}}_{3}$ was determined via measurements of the angular correlation of the electron--positron annihilation radiation. The topology of the electronlike FS does show nesting properties which are consistent with the modulated antiferromagnetic structure of the system. We determine the density of states at the Fermi energy ${N(E}_{F})$ and the electronic contribution to the gamma constant to be ${N(E}_{F})=16$ states/ Ryd /cell and $\ensuremath{\gamma}=2.7 ({\mathrm{m}\mathrm{J}/\mathrm{m}\mathrm{o}\mathrm{l}\mathrm{}\mathrm{K}}^{2}),$ respectively.

Measurement of the angular correlation of the electron-positron annihilation radiation complemented with ab initio calculations can provide decisive information about the character of $f$ electrons in actinide compounds. Our studies of the antiferromagnet ${\mathrm{U}\mathrm{G}\mathrm{a}}_{3}$ in the paramagnetic phase produce substantial evidence that an unconstrained $f$-electron itinerant description applies.

The L3 detector at LEP has been used to determine the number of light neutrino families by measuring the cross section of single photon even in e+e− collisions at energies near the Z0 resonance. We have observed 61 single photon candidates with more than 1.5 GeV of deposited energy in the barrel electromagnetic calorimeter, for a total integrated luminosity of 3.0 pb−1. From a likelihood fir to the single photon cross sections, we determin Nν=3.24 ± 0.46 (statistical) ±0.22 (systematic).

The K0SK±π∓ 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 η(1475) and f1(1420) mesons are observed and their contribution is separated by measuring the formation rates as a function of the photon virtuality Q2. The η(1475) is found to be dominant for Q2 ⩽ 0.01GeV2 and its two-photon width is measured to be 0.23±0.05 (stat.) ±0.05 (sys.) keV. At higher Q2, the f1(1420) is formed and decays to K*(892)K. The γγ coupling and form factor parameters of this state are measured to be Γγγ = 3.2±0.6 (stat.) ±0.7 (sys.) keV and Λ1 = 926±72 (stat.) ±32 (sys.) MeV, respectively.

We report a measurement of the time-dependent CP asymmetry of B[over ¯]^{0}→D_{CP}^{(*)}h^{0} decays, where the light neutral hadron h^{0} is a π^{0}, η, or ω meson, and the neutral D meson is reconstructed in the CP eigenstates K^{+}K^{-}, K_{S}^{0}π^{0}, or K_{S}^{0}ω. The measurement is performed combining the final data samples collected at the ϒ(4S) resonance by the BABAR and Belle experiments at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain (471±3)×10^{6} BB[over ¯] pairs recorded by the BABAR detector and (772±11)×10^{6} BB[over ¯] pairs recorded by the Belle detector. We measure the CP asymmetry parameters -η_{f}S=+0.66±0.10(stat)±0.06(syst) and C=-0.02±0.07(stat)±0.03(syst). These results correspond to the first observation of CP violation in B[over ¯]^{0}→D_{CP}^{(*)}h^{0} decays. The hypothesis of no mixing-induced CP violation is excluded in these decays at the level of 5.4 standard deviations.

We present a study of the structure of hadronic events recorded by the L3 detector at LEP at the center of mass energies of 161 and 172 GeV. The data sample corresponds to an integrated luminosity of 21.25 pb−1 collected during the high energy runs of 1996. The distributions of event shape variables and the energy dependence of their mean values are well reproduced by QCD models. From a comparison of the data with resummed O(αs2) QCD calculations, we determine the strong coupling constant at the two energies. Combining this with our earlier measurements we find that the strong coupling constant decreases with increasing energy as expected in QCD.

With a data sample of 86 000 Z → τ+τ−(γ) events collected in 1990 through 1993 we have measured the polarization of τ-leptons as a function of the production polar angle using the following 1-prong τ decay modes: τ−→e−vevτ, τ−→π−(K−)vτ, τ−→ϱ−vτandτ−→a1−vτ. We obtain for the ratio vector to axial-vector weak neutral couplings for electrons gVe/gAe=0.0791±0.0099(stat)±0.0025 (syst) and taus gVτ/gAτ=0.0752±0.0063 (stat)±0.0045 (syst) consistent with the hypothesis of e - τ universality. Assuming universality of the e - τ neutral current we determine the effective electroweak mixing angle to be sin2 θeffw = 0.2309 ± 0.0016.

Over the past two decades or so, the positron annihilation technique has successfully probed Fermi surface (FS) topologies in a variety of metals and alloy systems. However, in electronically complex systems, due to the relatively weak FS signals compared with those arising from annihilations from a large number of full bands, possible strong positron wave function comes into effect. Here, we introduce a new way of looking at the problem using maximum-entropy enhancement of the data. Test results from the simple FS picture of vanadium are presented.

We have measured the forward-backward asymmetry in e+e−→bband e+e−→cc processes using hadronic events containing muons or electrons. The data sample corresponds to 4100000 hadronic decays of the Z0. From a fit to the single lepton and dilepton p and pT spectra, we determine Abb=0.086±0.015±0.007andAcc=0.083±0.038±0.027 at the effective center-of-mass energy √s=91.24 GeV. These measurements yield a value of the electroweak mixing angle sin2θw=0.2336±0.0029.

We report on inclusive xc production in Z decays reconstructed via the decay mode Xc → J + γ. This analysis is based on 1.1 million hadronic Z events. Interpreting the observed signal as Xcl, we obtain a branching ratio Br(Z→ Xcl + X) = (7.5±2.9(stat.) ±0.6(sys.)) × 10−3. Assuming all events are produced in b decays we obtain Br(b→ Xcl + X) = (2.4 ± 0.9(stat.) ±0.2(sys.)) × 10−2. We also present an improved measurement of the branching ratio Br(Z → J + X) = (3.6 ± 0.5 (stat.) ± 0.4 (sys.)) × 10−3, obtained from dileptonic J decays.

We report on a general search for neutral and charged Higgs bosons with no assumption that the Higgs sector consists of a single doublet as in the minimal standard model. No signal inconsistent with background is observed in any of the decay channels analysed. From the results of direct searches, model independent limits on Higgs bremsstrahlung and on Higgs pair production from the Z0 are presented. We interpret the bremsstrahlung limits in the general two-doublet model. Z0 lineshape measurements further restrict the parameter space available in the two-doublet model. Finally, the results are interpreted in the framework of the minimal supersymmetric extension of the standard model.

A search for a Higgs boson produced in e^+e^- collisions in association with a Z boson and decaying into invisible particles is performed. Data collected at LEP with the L3 detector at centre-of-mass energies from 189 GeV to 209 GeV are used, corresponding to an integrated luminosity of 0.63/fb. Events with hadrons, electrons or muons with visible masses compatible with a Z boson and missing energy and momentum are selected. They are consistent with the Standard Model expectations. A lower limit of 112.3 GeV is set at 95% confidence level on the mass of the invisibly-decaying Higgs boson in the hypothesis that its production cross section equals that of the Standard Model Higgs boson. Relaxing this hypothesis, upper limits on the production cross section are derived.

The Interventional Radiology (IR) is a well established technique in medical domain aiming to obtain a good X-ray image quality while minimizing the radiation dose absorbed by patients and staff members. From a radioprotection point of view, these procedures are considered potentially harmful for interventional radiologists and medical staff. Individual monitoring of operators is very important and is performed by assessing effective dose, equivalent dose to the extremities and eye lens, with the use of passive dosimeters (e.g. TLDs) calibrated in terms of personal dose equivalent Hp (10), Hp (0.07) and Hp (3), respectively. In this work we will present a proposal for an innovative X-ray dosimeter prototype, capable of real-time measurements, packaged in a small form-factor, with wireless communication to be used for individual operators dosimetry during IR procedures. The proposed real-time dosimeter relies on CMOS Active Pixel Sensor, widely used in visible imaging applications. Some preliminary results on the characterization of CMOS active pixel sensors as diffused X-ray detectors during a typical IR session will be presented.

New measurements at a centre-of-mass energy s≃183 GeV of the hadronic photon structure function Fγ2(x) in the Q2 interval, 9 GeV2 ≤Q2≤30 GeV2, are presented. The data, collected in 1997 with the L3 detector, correspond to an integrated luminosity of 51.9 pb−1. Combining with the data taken at a centre-of-mass energy of 91 GeV, the evolution of Fγ2 with Q2 is measured in the Q2 range from 1.2 GeV2 to 30 GeV2. Fγ2 shows a linear growth with lnQ2; the value of the slope α−1dFγ2(Q2)/dlnQ2 is measured in two x bins from 0.01 to 0.2 and is somewhat higher than predicted.

We report on measurements of the triple-gauge-boson couplings of the W boson in e+e− collisions with the L3 detector at LEP. W-pair, single-W and single-photon events are analysed in a data sample corresponding to a total luminosity of 76.7 pb−1 collected at centre-of-mass energies between 161GeV and 183GeV. CP-conserving as well as both C- and P-conserving triple-gauge-boson couplings are determined. The results, in good agreement with the Standard-Model expectations, confirm the existence of the self coupling among the electroweak gauge bosons and constrain its structure.

We describe the sample of energetic single-photon events (Eγ > 15 GeV) collected by L3 in the 1991–1993 LEP runs. The event distributions agree with expectations from the Standard Model. The data are used to constrain the ZZγ coupling and to set an upper limit of 4.1 × 10−6, μB (90% C.L.) on the the magnetic moment of the τ neutrino.

The production of B∗ mesons in Z decays has been measured at LEP with the L3 detector. A sample of Z → bb events was obtained by tagging muons in 1.6 million hadronic Z decays collected in 1991, 1992 and 1993. A signal with a peak value of Eγ = 46.3 ± 1.9 (stat) MeV in the B rest frame energy spectrum was interpreted to come from the decay B∗ → γB. The inclusive production ratio of B∗ mesons relative to B mesons was determined from a fit to the spectrum to be NB∗(NB∗+ NB)= 0.76 ± 0.08 ± 0.06, where the first error is statistical and the second is systematic.

We measure the masses, decay widths and relative production rate of orbitally excited B mesons using 1.25 million hadronic Z decays recorded by the L3 detector. B-meson candidates are inclusively reconstructed and combined with charged pions produced at the primary event vertex. An excess of events above the expected background in the B\pi mass spectrum in the region 5.6-5.8 GeV is interpreted as resulting from the decay B_u,d^** -> B^(*)\pi, where B_u,d^** denotes a mixture of l=1 B-meson states containing a u or a d quark. A fit to the mass spectrum yields the masses and decay widths of the B_1^* and B_2^* spin states, as well as the branching fraction for the combination of l=1 states. In addition, evidence is presented for the existence of an excited B-meson state or mixture of states in the region 5.9-6.0 GeV.

We carry out measurements of the two-dimensional angular correlation of the positron annihilation radiation (2D-ACAR) to reconstruct the complex multisheet Fermi surface (FS) of the cubic rare-earth (RE) compound TmGa3. We discover a correlation between the antiferromagnetic structures and the nesting of the FS along the [110] directions. Moreover, we propose methods to estimate the density of states at the Fermi energy ( EF) and the electronic contribution to the specific heat [we obtain N(EF) = 13.6 states/Ryd cell and gamma = 2.4 mJ/mole K2].

The benefit of using a Maximum-Entropy deconvolution technique prior to reconstructing the three-dimensional momentum density from two-dimensional angular correlation of positron annihilation radiation (2DACAR) is highlighted. The technique is applied to experimental data for a single crystal of chromium in its paramagnetic phase. The resulting reconstructed momentum density features are significantly enhanced when the 2DACAR spectra are first deconvoluted, although there are artefacts present around p ∼ 0. It is also shown to agree well with the theoretical momentum density.

Inclusive J production in Z0 decays is observed via the leptonic decay mode J → ℓ+ℓ− (ℓ = e,μ). We measure the branching ratio Br(Z0 → J + X) = (4.1 ± 0.7 (stat.) ± 0.3 (sys.)) × 10−3. We have calculated the fraction of the J mesons from b-hadron decay and find a branching ratio of Br(b → J + X)= (1.3±0.2(stat.)±0.2(sys.)) × 10−2. We determine the average fractional energy of bottom hadrons 〈XE > = 0.70±0.03 (stat.)+0.02−0.01 (sys.) using the momentum spectrum of the J mesons. From a study of the angle between the J and the most energetic jet, we set an upper limit on the branching ratio Br(Z0 → qqg∗;g∗ → J + X) < 7.0 × 10−4at 90% confidence level.

We report on the first measurements of e+e− annihilations into hadrons and lepton pairs at centre-of-mass energies between 130 GeV and 140 GeV. In a total luminosity of 5 pb−1 collected with the L3 detector at LEP we select 1577 hadronic and 401 lepton-pair events. The measured cross sections and leptonic forward-backward asymmetries agree well with the Standard Model predictions.

Bose-Einstein correlations in W-pair production at LEP are investigated in a data sample of 629 pb^-1 collected by the L3 detector at centre-of-mass energies of 189-209 GeV. Bose-Einstein correlations between pions within a W decay are observed and found to be in good agreement with those in light-quark Z decay. No evidence is found for Bose-Einstein correlations between hadrons coming from different W's in the same event.

A new method for filtering three-dimensional reconstructed densities is proposed. The algorithm is tested with simulated spectra and employed to study the electronic structure of the rare-earth compound $\mathrm{La}{\mathrm{B}}_{6}$. For this system, momentum densities are reconstructed from theoretical and experimental two-dimensional angular correlation of electron-positron annihilation radiation (2D ACAR) spectra. The experimental results are in good agreement with the band structure calculated with the full-potential linearized augmented-plane-wave (FLAPW) method within the local-density approximation (LDA), apart from the detection of small electron pockets in the 15th band. It is also shown that, unlike the electron-positron enhancement, the electron-electron correlations affect noticeably the momentum density.

We present first evidence that the cosine of the CP-violating weak phase 2β is positive, and hence exclude trigonometric multifold solutions of the Cabibbo-Kobayashi-Maskawa (CKM) Unitarity Triangle using a time-dependent Dalitz plot analysis of B^{0}→D^{(*)}h^{0} with D→K_{S}^{0}π^{+}π^{-} decays, where h^{0}∈{π^{0},η,ω} denotes a light unflavored and neutral hadron. The measurement is performed combining the final data sets of the BABAR and Belle experiments collected at the ϒ(4S) resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain (471±3)×10^{6}BB[over ¯] pairs recorded by the BABAR detector and (772±11)×10^{6}BB[over ¯] pairs recorded by the Belle detector. The results of the measurement are sin2β=0.80±0.14(stat)±0.06(syst)±0.03(model) and cos2β=0.91±0.22(stat)±0.09(syst)±0.07(model). The result for the direct measurement of the angle β of the CKM Unitarity Triangle is β=[22.5±4.4(stat)±1.2(syst)±0.6(model)]°. The measurement assumes no direct CP violation in B^{0}→D^{(*)}h^{0} decays. The quoted model uncertainties are due to the composition of the D^{0}→K_{S}^{0}π^{+}π^{-} decay amplitude model, which is newly established by performing a Dalitz plot amplitude analysis using a high-statistics e^{+}e^{-}→cc[over ¯] data sample. CP violation is observed in B^{0}→D^{(*)}h^{0} decays at the level of 5.1 standard deviations. The significance for cos2β>0 is 3.7 standard deviations. The trigonometric multifold solution π/2-β=(68.1±0.7)° is excluded at the level of 7.3 standard deviations. The measurement resolves an ambiguity in the determination of the apex of the CKM Unitarity Triangle.

A determination of the number of light neutrino families performed by measuring the cross section of single photon production in e+e− collision near the Z resonance is reported. From an integrated luminosity of 100pb−1, collected during the years 1991–94, we have observed 2091 single photon candidates with an energy above 1 GeV in the polar angular region 45°<θγ<135°. From a maximum likelihood fit to the single photon cross section, the Z decay width into invisible particles is measured to be Γinv=498±12(stat)±12(sys)MeV. Using the Standard Model couplings of neutrinos to the Z, the number of light neutrino species is determined to be Nν=2.98±0.07(stat)±0.07(sys).

An analysis of single and multi-photon events with missing energy is performed using data collected with the L3 detector at LEP at centre-of-mass energies around 183GeV, for a total of 55.3 pb−1 of integrated luminosity. The results obtained are in good agreement with the Standard Model prediction and are used to derive the value for the e+e−→νν̄γ(γ) cross section as well as upper limits on cross sections of new physics processes. Several interpretations in supersymmetric models providing new limits on the masses of the lightest neutralino and of the gravitino are presented.

Using the L3 detector, the branching ratio BR(b → πνX) has been measured using a sample of Z → bb events tagged by high momentum and high transverse momentum leptons in one hemisphere and with missing energy in the opposite hemisphere. From a sample of 948 000 hadronic events we find BR(b → πνX) = (2.4 ± 0.7 (stat.) ± 0.8 (syst.))%.

A search for rare charmless decays of Bd0 and Bs0 mesons has been performed in the exclusive channels Bd(s)0 →ηη, Bd(s)0 →ηπ0 and Bd(s)0 →π0π0. The data sample consisted of three million hadronic Z decays collected by the L3 experiment at LEP from 1991 through 1994. No candidate event has been observed and the following upper limits at 90% confidence level on the branching ratios have been set: Br(B()d→ηη) <4.1 x 10−4, Br(B()s→ηη) < 1.5 x 10−3, Br(B()d→ηφ()) < 2.5 x 10−4, Br(B()s→ηphi;()) < 1.0 x 10−3, Br(B()d→phi;()phi;()) < 6.0 x 10−5, Br(B()s→phi;()phi;()) < 2.1 x 10−4. These are the first experimental limits on Bd0→ηη and on the Bs0 neutral charmless modes.

We report on measurements of the mass and total decay width of the W boson with the L3 detector at LEP. W-pair events produced in $\mathrm{e^+e^-}$ interactions between 161 GeV and 183 GeV centre-of-mass energy are selected in a data sample corresponding to a total luminosity of 76.7 pb$^{-1}$. Combining all final states in W-pair production, the mass and total decay width of the W boson are determined to be $\mathrm{M_W}=80.61\pm0.15$ GeV and $\Gamma_{\mathrm{W}}=1.97\pm0.38$ GeV, respectively.

We have measured the cross-section of the production of single photon events in e+e− collisions near the Z0 resonance. For an integrated luminosity of 9.6 pb−1, we have observed 202 single photon candidates with energy between 0.9 and 3.5 GeV in the polar angular region between 45° and 135°. Assuming that the only stable weakly interacting particles are light neutrinos with standard model couplings, we determine the number of light neutrino species to be Nv = 3.14 ± 0.24 (stat.)±0.12 (syst.). This corresponds to an invisible Z0 width of Γinv = 524 ± 40 ± 20 MeV.

We present results obtained from a study of the structure of hadronic events recorded by the L3 detector at various centre-of-mass energies. The distributions of event shape variables and the energy dependence of their mean values are measured from 30GeV to 189GeV and compared with various QCD models. The energy dependence of the moments of event shape variables is used to test a power law ansatz for the non-perturbative component. We obtain a universal value of the non-perturbative parameter alpha_0 = 0.537 +/- 0.073. From a comparison with resummed O(alpha_s^2) QCD calculations, we determine the strong coupling constant at each of the selected energies. The measurements demonstrate the running of alpha_s as expected in QCD with a value of alpha_s(m_Z) = 0.1215 +/- 0.0012 (exp) +/- 0.0061 (th).

The structure functions of real and virtual photons are derived from cross section measurements of the reaction e+e−→e+e−+ hadrons at LEP. The reaction is studied at s≃91GeV with the L3 detector. One of the final state electrons is detected at a large angle relative to the beam direction, leading to Q2 values between 40 GeV2 and 500 GeV2. The other final state electron is either undetected or it is detected at a four-momentum transfer squared P2 between 1 GeV2 and 8 GeV2. These measurements are compared with predictions of the Quark Parton Model and other QCD based models.

The modeled performance of the Alpha Magnetic Spectrometer (AMS) as a high energy (0.3 to 100 GeV) gamma-ray detector is described, and its gamma ray astrophysics objectives are discussed.

A more precise determination of the B0-B0 mixing parameter in Z0 decays based on a fourfold increase in statistics has been made using the 1990 and 1991 L3 data. The analysis of the dilepton events, muons and electrons, gives: χB = 0.121 ± 0.017 (stat) ± 0.006 (sys). Using the value of χd measured at the γ(4S) we derive the following limit for χs:χs > 0.16 (90% CL).

We have measured the total and differential cross sections of the reaction e+e− → γγ(γ) at center-of-mass energies around 91 GeV, with an integrated luminosity of 14.2 pb−1. The results are in good agreement with QED predictions. We set lower limits, at 95% confidence level, on the QED cutoff parameters of Λ+ > 139 GeV, Λ− > 108 GeV and on the mass of an excited electron of me∗> 127GeV. We searched for Z0 rare decays with photonic signitures in the final state. Upper limits, at 95% confidence level, for branching ratio of Z0 decaying into π0γ/γγ, νγ and γγγ are 1.2 × 10−4, 1.8 × 10−4, 3.3 × 10−5 respectively.