-
P. Achard,
O Adriani,
M. Aguilar-Benitez,
M. van den Akker,
J Alcaraz,
G. Alemanni,
J. Allaby,
A Aloisio,
M G Alviggi,
H Anderhub, [......],
J Zhao,
S J Zhou,
G Y Zhu,
R Y Zhu,
Q. Q. Zhu,
H L Zhuang,
A. Zichichi,
B. Zimmermann,
M. Zoeller,
A. N. M. Zwart
[show abstract]
[hide abstract]
ABSTRACT: Context. Primary cosmic rays experience multiple deflections in the non-uniform galactic and heliospheric magnetic fields which may generate anisotropies. Aims. A study of anisotropies in the energy range between 100 and 500 GeV is performed. This energy range is not yet well explored. Methods. The L3 detector at the CERN electron-positron collider, LEP, is used for a study of the angular distribution of atmospheric muons with energies above 20 GeV. This distribution is used to investigate the isotropy of the time-dependent intensity of the primary cosmic-ray flux with a Fourier analysis. Results. A small deviation from isotropy at energies around 200 GeV is observed for the second harmonics at the solar frequency. No sidereal anisotropy is found at a level above 10(-4). The measurements were performed in the years 1999 and 2000.
Astronomy and Astrophysics 03/2008; 488:1093-1100. · 4.59 Impact Factor
-
P. Achard,
O. Adriani,
M. Aguilar-Benitez,
J. Alcaraz,
G. Alemanni,
J. Allaby,
A. Aloisio,
M.G. Alviggi,
H. Anderhub,
V.P. Andreev, [......], Y. Zalite,
Z.P. Zhang,
J. Zhao,
G.Y. Zhu,
R.Y. Zhu,
H.L. Zhuang,
A. Zichichi,
B. Zimmermann,
M. Zöller,
The Collaboration
[show abstract]
[hide abstract]
ABSTRACT: Measurements of inclusive production of the Λ, Ξ- and Ξ*(1530) baryons in two-photon collisions with the L3 detector at LEP are presented. The inclusive differential cross sections
for Λ and Ξ- are measured as a function of the baryon transverse momentum, pt, and pseudo-rapidity, η. The mean number of Λ, Ξ- and Ξ*(1530) baryons per hadronic two-photon event is determined in the kinematic range 0.4GeV<pt<2.5GeV, |η|<1.2. Overall agreement with the theoretical models and Monte Carlo predictions is observed. A search for inclusive
production of the pentaquark θ+(1540) in two-photon collisions through the decay θ+→pK0
S is also presented. No evidence for production of this state is found.
European Physical Journal C 12/2006; 49(2):395-410. · 3.63 Impact Factor
-
P. Achard,
O Adriani,
M. Aguilar-Benitez,
M. van den Akker,
J Alcaraz,
G. Alemanni,
J. Allaby,
A Aloisio,
M G Alviggi,
H Anderhub, [......],
J Zhao,
S J Zhou,
G Y Zhu,
R Y Zhu,
Q. Q. Zhu,
H L Zhuang,
A. Zichichi,
B. Zimmermann,
M. Zoller,
A. N. M. Zwart
[show abstract]
[hide abstract]
ABSTRACT: 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.
Astroparticle Physics 03/2006; 25:298-310. · 3.22 Impact Factor
-
P. Cwetanski,
T. Akesson,
F. Anghinolfi,
E. Arik,
O.K. Baker,
E. Banas,
S. Baron,
D. Benjamin,
H. Bertelsen,
V. Bondarenko, [......],
S. Soutchkov,
G. Sprachmann,
V. Tikhomirov,
R. Van Berg,
V.I. Vassilakopoulos,
L. Vassilieva,
C. Wang,
H.H. Williams, A. Zalite,
Y. Zalite
[show abstract]
[hide abstract]
ABSTRACT: The Transition Radiation Tracker (TRT) sits at the outermost part of the ATLAS Inner Detector, encasing the Pixel Detector and the Semi-Conductor Tracker (SCT). The TRT combines charged particle track reconstruction with electron identification capability. This is achieved by layers of xenon-filled straw tubes with periodic radiator foils or fibers providing TR photon emission. The design and choice of materials have been optimized to cope with the harsh operating conditions at the LHC, which are expected to lead to an accumulated radiation dose of 10 Mrad and a neutron fluence of up to 2middot10<sup>14</sup> n/cm<sup>2 </sup> after ten years of operation. The TRT comprises a barrel containing 52 000 axial straws and two end-cap parts with 320 000 radial straws. The total of 420 000 electronic channels (two channels per barrel straw) allows continuous tracking with many projective measurements (more than 30 straw hits per track). The assembly of the barrel modules in the US has recently been completed, while the end-cap wheel construction in Russia has reached the 50% mark. After testing at the production sites and shipment to CERN, all modules and wheels undergo a series of quality and conformity measurements. These acceptance tests survey dimensions, wire tension, gas-tightness, high-voltage stability and gas-gain uniformity along each individual straw. This paper gives details on the acceptance criteria and measurement methods. An overview of the most important results obtained to-date is also given
IEEE Transactions on Nuclear Science 01/2006; · 1.45 Impact Factor
-
P. Achard,
O Adriani,
M. Aguilar-Benitez,
M. van den Akker,
J Alcaraz,
G. Alemanni,
J. Allaby,
A Aloisio,
M G Alviggi,
H Anderhub, [......],
J Zhao,
S J Zhou,
G Y Zhu,
R Y Zhu,
Q. Q. Zhu,
H L Zhuang,
A. Zichichi,
B. Zimmermann,
M. Zoller,
A. N. M. Zwart
[show abstract]
[hide abstract]
ABSTRACT: The shadowing of high-energy cosmic rays by the Moon has been observed with a significance of 9.4 standard deviations with the L3 + C muon spectrometer at CERN. A significant effect of the Earth magnetic field is observed. Since no event deficit on the east side of the Moon has been observed, an upper limit at 90% confidence level on the antiproton to proton ratio of 0.11 is obtained for primary energies around 1 TeV. © 2005 Elsevier B.V. All rights reserved.
Astroparticle Physics 03/2005; 23:411-434. · 3.22 Impact Factor
-
P. Achard,
O Adriani,
M. Aguilar-Benitez,
M. van den Akker,
J Alcaraz,
G. Alemanni,
J. Allaby,
A Aloisio,
M G Alviggi,
H Anderhub, [......],
J Zhao,
S J Zhou,
G Y Zhu,
R Y Zhu,
H L Zhuang,
Q. Q. Zhu,
A. Zichichi,
B. Zimmermann,
M. Zoller,
A. N. M. Zwart
[show abstract]
[hide abstract]
ABSTRACT: The absolute muon flux between 20 and 3000 GeV is measured with the L3 magnetic muon spectrometer for zenith angles ranging from 0degrees to 58degrees. Due to the large exposure of about 150 m**2 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 and 500 GeV, and the average vertical muon charge ratio is found to be 1.285 +/- 0.003(stat.) +/-0.019(syst.).
(C) 2004 Elsevier B.V. All rights reserved.
Physics Letters B 08/2004; 598:15-32. · 3.95 Impact Factor
-
P. Bagnaia,
A. Bajo,
G. Baksay,
L. Baksay,
S. V. Baldew,
S. Banerjee,
A. Barczyk,
R. Barillere,
P. Bartalini,
M. Basile, [......],
A. Zalite, Y. Zalite,
Z. P. Zhang,
J. Zhao,
G. Y. Zhu,
R. Y. Zhu,
H. L. Zhuang,
A. Zichichi,
B. Zimmermann,
M. Zoller
Physics Letters B 03/2004; 585:53-62. · 3.95 Impact Factor
-
P. Bagnaia,
A. Bajo,
G. Baksay,
L. Baksay,
S. V. Baldew,
S. Banerjee,
A. Barczyk,
R. Barillere,
P. Bartalini,
M. Basile, [......],
A. Zalite, Y. Zalite,
Z. P. Zhang,
J. Zhao,
G. Y. Zhu,
R. Y. Zhu,
H. L. Zhuang,
A. Zichichi,
B. Zimmermann,
M. Zoller
[show abstract]
[hide abstract]
ABSTRACT: 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.
Physics Letters B 10/2002; 547:139-150. · 3.95 Impact Factor
-
P. Bagnaia,
A. Bajo,
G. Baksay,
L. Baksay,
S. V. Baldew,
S. Banerjee,
A. Barczyk,
R. Barillere,
P. Bartalini,
M. Basile, [......],
A. Zalite, Y. Zalite,
Z. P. Zhang,
J. Zhao,
G. Y. Zhu,
R. Y. Zhu,
H. L. Zhuang,
A. Zichichi,
B. Zimmermann,
M. Zoller
[show abstract]
[hide abstract]
ABSTRACT: Single W boson production in electron-positron collisions is studied
with the L3 detector at centre-of-mass energies between 192 GeV and 209
GeV. Events with two acoplanar hadronic jets or a single energetic
lepton are selected, and the single W cross section is measured.
Combining the results with measurements at lower centre-of-mass
energies, the ratio of the measured cross section to the Standard Model
expectation is found to be 1.12^{+0.11}_{-0.10}+/-0.03. From all single
W data, the WWgamma gauge coupling parameter kappa_gamma is measured to
be 1.116^{+0.082}_{-0.086}+/-0.068.
Physics Letters B 10/2002; 547:151-163. · 3.95 Impact Factor
-
A. A. Vorobyov,
M. Wadhwa,
W. Wallraff,
X. L. Wang,
Z. M. Wang,
M. Weber,
P. Wienemann,
H. Wilkens,
S. Wynhoff,
L. Xia, [......], Y. Zalite,
Z. P. Zhang,
J. Zhao,
G. Y. Zhu,
R. Y. Zhu,
H. L. Zhuang,
A. Zichichi,
G. Zilizi,
B. Zimmermann,
M. Z. Zoller
[show abstract]
[hide abstract]
ABSTRACT: The process e+e- -> W+ W- gamma 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 GeV to 207
GeV, are presented. The W+W- gamma 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- --> nu nubar gamma
gamma.
Physics Letters B 01/2002; 527:29-38. · 3.95 Impact Factor
-
Collaboration,
M. Acciarri,
P. Achard,
O. Adriani,
M. Aguilar-Benitez,
J. Alcaraz,
G. Alemanni,
J. Allaby,
A. Aloisio,
M. G. Alviggi, [......],
S. C. Yeh,
A. Zalite, Y. Zalite,
Z. P. Zhang,
G. Y. Zhu,
R. Y. Zhu,
A. Zichichi,
G. Zilizi,
B. Zimmermann,
M. Zöller
[show abstract]
[hide abstract]
ABSTRACT: The production of c and b quarks /γγ 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-
cc¯X) and
σ(e+e--->e+e-
bb¯X) are measured and compared to next-to-leading order
perturbative QCD calculations. The cross section of b production is
measured in /γγ collisions for the first time. It is in
excess of the QCD prediction by a factor of three.
Physics Letters B 02/2001; 503:10-20. · 3.95 Impact Factor
-
S Schael,
R Barate,
R Bruneliere,
I De Bonis,
D Decamp,
C Goy,
S Jezequel,
JP Lees,
F Martin,
E Merle, [......],
L Zivkovic,
S. Heinemeyer,
A. Pilaftsis,
G. Weiglein,
LEP Collaboration,
ALEPH Collaboration,
DELPHI Collaboration,
L3 Collaboration,
OPAL Collaboration,
LEP Working Grp Higgs Boson Search
-
S Schael,
R Barate,
R Bruneliere,
D Buskulic,
I De Bonis,
D Decamp,
P Ghez,
C Goy,
S Jezequel,
JP Lees, [......],
RK Yamamoto,
XQ Yang,
J Yashima,
SJ Yellin,
CC Young,
H Yuta,
G Zapalac,
RW Zdarko,
C Zeitlin,
J Zhou
Michael Williams.
-
O Adriani,
M. Aguilar-Benitez,
J Alcaraz,
G. Alemanni,
J. Allaby,
A Aloisio,
M G Alviggi,
H Anderhub,
V P Andreev,
F Anselmo, [......], Y. Zalite,
Z P Zhang,
J Zhao,
G Y Zhu,
R Y Zhu,
H L Zhuang,
A. Zichichi,
B. Zimmermann,
M. Zoller,
P. Achard
[show abstract]
[hide abstract]
ABSTRACT: The CP-conserving triple-gauge-boson couplings, g(1)(Z), kappa(gamma), lambda(gamma), g(5)(Z), kappa(Z) and lambda(Z) are measured using hadronic and semi-leptonic W-pair events selected in 629 pb(-1) of data collected at LEP with the L3 detector at centre-of-mass energies between 189 and 209 GeV. The results are combined with previous L3 measurements based on data collected at lower centre-of-mass energies and with the results from single-W production and from events with a single-photon and missing energy. Imposing the constraints kappa(Z) = g(1)(Z) - tan(2) thetaw(kappa(gamma) - 1) and lambda(Z) = lambda(gamma), we obtain for the C and P conserving couplings the results:
-
P. Achard,
O Adriani,
M. Aguilar-Benitez,
J Alcaraz,
G. Alemanni,
J. Allaby,
A Aloisio,
M G Alviggi,
H Anderhub,
V P Andreev, [......],
A Zalite, Y. Zalite,
Z P Zhang,
J Zhao,
G Y Zhu,
R Y Zhu,
H L Zhuang,
A. Zichichi,
B. Zimmermann,
M Zöller
[show abstract]
[hide abstract]
ABSTRACT: The e+e-→e+e-hadrons reaction, where one of the two electrons is detected in a low polar-angle calorimeter, is analysed in order to measure the hadronic photon structure function F2 γ. The full high-energy and high-luminosity data set, collected with the L3 detector at centre-of-mass energies 189 GeV≤√s≤209 GeV, corresponding to an integrated luminosity of 608 pb-1 is used. The Q2 range 11 GeV 2≤Q2≤34 GeV2 and the x range 0.006≤x≤0.556 are considered. The data are compared with recent parton density functions.
-
P. Achard,
O Adriani,
M. Aguilar-Benitez,
J Alcaraz,
G. Alemanni,
J. Allaby,
A Aloisio,
M G Alviggi,
H Anderhub,
V P Andreev, [......],
A Zalite, Y. Zalite,
Z P Zhang,
J Zhao,
G Y Zhu,
R Y Zhu,
H L Zhuang,
A. Zichichi,
B. Zimmermann,
M. Zoller
[show abstract]
[hide abstract]
ABSTRACT: Inclusive jet production, e+e(-) --> e(+)e(-) jet X, is studied using 560 pb(-1) of data collected at LEP with the L3 detector at centre-of-mass energies between 189 and 209 GeV. The inclusive differential cross section is measured using a k(1), jet algorithm as a function of the jet transverse momentum, p(t), in the range 3 < p(t) < 50 GeV for a pseudorapidity, eta, in the range -1 < eta < 1. This cross section is well represented by a power law. For high p(t), the measured cross section is significantly higher than the NLO QCD predictions, as already observed for inclusive pi(+/-) and pi(0) production. (C) 2004 Published by Elsevier B.V.
Physics Research Publications.
-
P. Achard,
O Adriani,
M. Aguilar-Benitez,
J Alcaraz,
G. Alemanni,
J. Allaby,
A Aloisio,
M G Alviggi,
H Anderhub,
V P Andreev, [......],
A Zalite, Y. Zalite,
Z P Zhang,
J Zhao,
G Y Zhu,
R Y Zhu,
H L Zhuang,
A. Zichichi,
B. Zimmermann,
M. Zoller
[show abstract]
[hide abstract]
ABSTRACT: 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(-) nunugamma(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-nu = 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. (C) 2004 Published by Elsevier B.V.
Physics Research Publications.
-
P. Achard,
O Adriani,
M. Aguilar-Benitez,
J Alcaraz,
G. Alemanni,
J. Allaby,
A Aloisio,
M G Alviggi,
H Anderhub,
V P Andreev, [......],
A Zalite, Y. Zalite,
Z P Zhang,
J Zhao,
G Y Zhu,
R Y Zhu,
H L Zhuang,
A. Zichichi,
B. Zimmermann,
M. Zoller
[show abstract]
[hide abstract]
ABSTRACT: Events from the e(+)e(-) --> Zgamma process with hard initial-state radiation collected with the L3 detector at centre-of-mass energies between 183 and 209 GeV are used to measure the mass of the Z boson. Decays of the Z boson into hadrons or muon pairs are considered and the Z mass is determined to be 91.272 +/- 0.032(stat) +/- 0.033(syst) GeV, in agreement with the value measured at the Z resonance. Alternatively, assuming this measured value of the Z mass, the method determines the LEP centre-of-mass energy, found to be 175 +/- 68(stat) +/- 68(syst) MeV lower than the nominal value. (C) 2004 Published by Elsevier B.V.
Physics Research Publications.
-
P. Achard,
O Adriani,
M. Aguilar-Benitez,
J Alcaraz,
G. Alemanni,
J. Allaby,
A Aloisio,
M G Alviggi,
H Anderhub,
V P Andreev, [......],
A Zalite, Y. Zalite,
Z P Zhang,
J Zhao,
G Y Zhu,
R Y Zhu,
H L Zhuang,
A. Zichichi,
B. Zimmermann,
M. Zoller
[show abstract]
[hide abstract]
ABSTRACT: A search is performed in symmetric 3-jet hadronic Z-decay events for evidence of colour singlet production or colour reconnection effects. Asymmetries in the angular separation of particles are found to be sensitive indicators of such effects. Upper limits on the level of colour singlet production or of colour reconnection effects are established for a variety of models. (C) 2003 Published by Elsevier B.V.
Physics Research Publications.
-
P. Achard,
O Adriani,
M. Aguilar-Benitez,
J Alcaraz,
G. Alemanni,
J. Allaby,
A Aloisio,
M G Alviggi,
H Anderhub,
V P Andreev, [......],
A Zalite, Y. Zalite,
Z P Zhang,
J Zhao,
G Y Zhu,
R Y Zhu,
H L Zhuang,
A. Zichichi,
B. Zimmermann,
M. Zoller
[show abstract]
[hide abstract]
ABSTRACT: Scalar partners of quarks and leptons, predicted in supersymmetric models, are searched for in e(+)e(-) collisions at centre-of-mass energies between 192 and 209 GeV 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. (C) 2003 Published by Elsevier B.V.
Physics Research Publications.
