Showing papers by "Jianming Qian published in 1992"
TL;DR: In this paper, the number of light neutrino species is found to be Nv=3.30% CL with the constraints of the standard electroweak model, which rules out the possibility of a fourth type of LN at 98% CL.
234 citations
TL;DR: In this paper, neutral heavy leptons that are isosinglets under the standard SU (2)L gauge group were searched for and no evidence for a signal has been found and the limit Br(NSu0 → vlNl) < 3 x 10−5 at the 95% CL for mass range from 3 GeV up to Mz.
99 citations
TL;DR: In this article, the structure of hadronic events from Z ≥ 0 decay is studied by measuring event shape variables, factorial moments, and the energy flow distribution, after correction for detector effects and initial and final state radiation, compared with the predictions of different QCD Monte Carlo programs with optimized parameter values.
Abstract: 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.
66 citations
TL;DR: In this article, 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 Z 0 decays is presented.
64 citations
TL;DR: In this article, the authors present a measurement of the inclusive jet cross section in {ital {bar p}p} collisions at {radical}{ital s} = 1.8 TeV at the Fermilab Tevatron using the Collider Detector.
Abstract: We present a measurement of the inclusive jet cross section in {ital {bar p}p} collisions at {radical}{ital s} =1.8 TeV at the Fermilab Tevatron using the Collider Detector at Fermilab. Good agreement is seen with the predictions of recent next-to-leading-order ({ital O}({alpha}{sub {ital s}}{sup 3})) QCD predictions. The dependence of the cross section on clustering cone size is reported for the first time. An improved limit on {Lambda}{sub {ital c}}, a term characterizing possible quark substructure, is set at 1.4 TeV (95% C.L.).
54 citations
CERN1, Istituto Nazionale di Fisica Nucleare2, Massachusetts Institute of Technology3, ETH Zurich4, Purdue University5, University of California, San Diego6, Northeastern University7, Paul Scherrer Institute8, Radboud University Nijmegen9, Harvard University10, Petersburg Nuclear Physics Institute11, University of Michigan12, University of Alabama13, University of Science and Technology of China14, Lawrence Livermore National Laboratory15, Argonne National Laboratory16
01 Dec 1992-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the design and operation of precision drift chambers with multisampling as well as the concepts and methods for reaching an extraordinary degree of precision in mechanics and calibration are described.
Abstract: The design and operation of precision drift chambers with multisampling as well as the concepts and methods for reaching an extraordinary degree of precision in mechanics and calibration are described. Specific instruments were developed for this purpose. The concept of reproducible positioning and the implementation to 30 μm accuracy, showing stability over three years, is given. Calibration and analysis with UV-laser and cosmic test measurements are outlined with the critical results. The experience of calibration and reliability of the large system in an actual L3 running experiment is analyzed. The resolution under “battle conditions” at LEP resulted in Δp p = (2.50±0.04)% at 45.6 GeV and will be presented in detail. The concept is well suited for future TeV energies.
40 citations
TL;DR: In this article, the analysis of the reactions e+e−→l+l−(nγ) (l=e,μ,τ) was performed and four events were observed, one e−e−γγ and three μ+μ −γγ with the invariant mass of the photon pairs close to 60 GeV.
35 citations
TL;DR: 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 Z 0 resonance as mentioned in this paper.
29 citations
TL;DR: In this paper, 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.
23 citations
TL;DR: In this paper, the fraction of the J mesons from b-hadron decay was calculated and a branching ratio of Br(b → J + X) = (1.3±0.2(stat.)± 0.3 (sys.)) × 10−3.
23 citations
TL;DR: In this paper, the forward-backward asymmetry of the Z 0.2336±0.0029 hadronic decays of the single lepton and dilepton p and pT spectra was measured using hadronic events containing muons or electrons.
TL;DR: In this article, a sample of e+e− annihilation events collected at the Z resonance corresponding to an integrated luminosity of 11.2 pb−1 was used to search for γX final states where X represents stable, weakly interacting particles and the energy of the photon is greater than 1 2 E beam.
TL;DR: In this paper, the authors present a study of the inclusive η production based on 300 000 hadronic Z 0 decays and find that the measured inclusive momentum distribution can be reproduced by parton shower Monte Carlo programs and also by an analytical QCD calculation.
TL;DR: A more precise determination of the B0-B 0 mixing parameter in Z0 decays based on a fourfold increase in statistics has been made using the 1990 and 1991 L3 data as mentioned in this paper.
TL;DR: In this article, a search for the standard model neutral Higgs boson is described, and data collected during 1990 and 1991, corresponding to 408 000 hadronic decays of the Z°, were used.