Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measurements of Cross Sections and Forward-Backward Asymmetries at the Z
  Resonance and Determination of Electroweak Parameters   We report on measurements of hadronic and leptonic cross sections and
leptonic forward-backward asymmetries performed with the L3 detector in the
years 1993-95. A total luminosity of 103 pb^-1 was collected at centre-of-mass
energies \sqrt{s} ~ m_Z and \sqrt{s} ~ m_Z +/- 1.8 GeV which corresponds to 2.5
million hadronic and 245 thousand leptonic events selected. These data lead to
a significantly improved determination of Z parameters. From the total cross
sections, combined with our measurements in 1990-92, we obtain the final
results: m_Z = 91189.8 +/- 3.1 MeV, Gamma_Z = 2502.4 +/- 4.2 MeV, Gamma_had =
1741.1 +/- 3.8 MeV, Gamma_l = 84.14 +/- 0.17 MeV. An invisible width of
Gamma_inv = 499.1 +/- 2.9 MeV is derived which in the Standard Model yields for
the number of light neutrino species N_nu = 2.978 +/- 0.014. Adding our results
on the leptonic forward-backward asymmetries and the tau polarisation, the
effective vector and axial-vector coupling constants of the neutral weak
current to charged leptons are determined to be \bar{g}_V^l = -0.0397 +/-
0.0017 and \bar{g}_A^l = -0.50153 +/- 0.00053.Including our measurements of the
Z -> b \bar{b} forward-backward and quark charge asymmetries a value for the
effective electroweak mixing angle of sin^2\bar{\theta}_W = 0.23093 +/- 0.00066
is derived. All these measurements are in good agreement with the Standard
Model of electroweak interactions. Using all our measurements of electroweak
observables an upper limit on the mass of the Standard Model Higgs boson of m_H
< 133 GeV is set at 95% confidence level.

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The categories of this paper are: hep-th
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The categories of this paper are: chem-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: eess
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The categories of this paper are: atom-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: adap-org
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The categories of this paper are: hep-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: supr-con
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The categories of this paper are: cmp-lg
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The categories of this paper are: nucl-ex
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The categories of this paper are: gr-qc
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The categories of this paper are: physics
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The categories of this paper are: funct-an
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The categories of this paper are: nucl-th