Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measurements of $B_c^+$ production and mass with the $B_c^+ \to J/\psi
  \pi^+$ decay   Measurements of $B_c^+$ production and mass are performed with the decay mode
$B_c^+ \to J/\psi \pi^+$ using 0.37 fb$^{-1}$ of data collected in $pp$
collisions at $\sqrt{s}=7$ TeV by the LHCb experiment. The ratio of the
production cross-section times branching fraction between the $B_c^+ \to J/\psi
\pi^+$ and the $B^+ \to J/\psi K^+$ decays is measured to be $(0.68 \pm
0.10\,({\rm stat.}) \pm 0.03\,({\rm syst.}) \pm 0.05\,({\rm lifetime}))$% for
$B_c^+$ and $B^+$ mesons with transverse momenta $p_{\rm T}>4 $GeV/$c$ and
pseudorapidities $2.5<\eta<4.5$. The $B_c^+$ mass is directly measured to be
$6273.7 \pm 1.3\,({\rm stat.}) \pm 1.6 \,({\rm syst.})$ MeV/$c^2$, and the
measured mass difference with respect to the $B^+$ meson is $M(B_c^+)-M(B^+) =
994.6 \pm 1.3\,({\rm stat.}) \pm 0.6\,({\rm syst.})$ MeV/$c^2$.

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The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
13
The categories of this paper are: quant-ph
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The categories of this paper are: chem-ph
16
The categories of this paper are: stat
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
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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: acc-phys
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The categories of this paper are: physics
7
The categories of this paper are: hep-th
6
The categories of this paper are: astro-ph
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The categories of this paper are: solv-int