Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observation of the Production of a W Boson in Association with a Single
  Charm Quark   The first observation of the production of a $W$ boson with a single charm
quark ($c$) jet in $p\bar{p}$ collisions at $\sqrt{s}=1.96 {\rm TeV}$ is
reported. The analysis uses data corresponding to 4.3 fb$^{-1}$, recorded with
the CDF II detector at the Fermilab Tevatron. Charm quark candidates are
selected through the identification of an electron or muon from charm-hadron
semileptonic decay within a hadronic jet, and a $Wc$ signal is observed with a
significance of 5.7 standard deviations. The production cross section
$\sigma_{Wc}(p_{Tc}>20 {\rm GeV}/c, |\eta_c|<1.5)\times B(W\rightarrow
\ell\nu)$ is measured to be $13.6^{+3.4}_{-3.1} {\rm pb}$ and is in agreement
with theoretical expectations. From this result the magnitude of the
quark-mixing matrix element $V_{cs}$ is derived, $|V_{cs}|=1.08\pm0.16$ along
with a lower limit of $|V_{cs}|>0.71$ at the 95% confidence level, assuming
that the $Wc$ production through $c$ to $s$ quark coupling is dominant.

16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
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The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
18
The categories of this paper are: econ
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
4
The categories of this paper are: cond-mat
25
The categories of this paper are: patt-sol
6
The categories of this paper are: astro-ph
13
The categories of this paper are: quant-ph
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The categories of this paper are: bayes-an
20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph