Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Direct Measurement of the Top Quark Charge at Hadron Colliders   We consider photon radiation in tbar-t events at the upgraded Fermilab
Tevatron and the CERN Large Hadron Collider (LHC) as a tool to measure the
electric charge of the top quark. We analyze the contributions of tbar-t-gamma
production and radiative top quark decays to p-p, pbar-p -> gamma l^+/- nu
bbar-b jj, assuming that both b-quarks are tagged. With 20~fb^{-1} at the
Tevatron, the possibility that the ``top quark'' discovered in Run I is
actually an exotic charge -4/3 quark can be ruled out at the 95% confidence
level. At the LHC, it will be possible to determine the charge of the top quark
with an accuracy of about 10%.

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The categories of this paper are: quant-ph
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The categories of this paper are: q-fin
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The categories of this paper are: mtrl-th
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The categories of this paper are: ao-sci
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The categories of this paper are: cond-mat
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The categories of this paper are: q-bio
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The categories of this paper are: supr-con
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The categories of this paper are: solv-int
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The categories of this paper are: chem-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: stat
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The categories of this paper are: astro-ph
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The categories of this paper are: nlin
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The categories of this paper are: hep-ex
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The categories of this paper are: eess