Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The pion form factor from first principles   We calculate the electromagnetic form factor of the pion in quenched lattice
QCD. The non-perturbatively improved Sheikoleslami-Wohlert lattice action is
used together with the ${\mathcal O}(a)$ improved current. We calculate form
factor for pion masses down to $m_\pi = 360 MeV$. We compare the mean square
radius for the pion extracted from our form factors to the value obtained from
the 'Bethe Salpeter amplitude'. Using (quenched) chiral perturbation theory, we
extrapolate our results towards the physical pion mass.

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The categories of this paper are: plasm-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: adap-org
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The categories of this paper are: math
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The categories of this paper are: stat
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The categories of this paper are: chao-dyn
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The categories of this paper are: acc-phys
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The categories of this paper are: math-ph
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The categories of this paper are: solv-int
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The categories of this paper are: bayes-an
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The categories of this paper are: funct-an
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The categories of this paper are: econ
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The categories of this paper are: comp-gas
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The categories of this paper are: q-fin
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The categories of this paper are: gr-qc
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The categories of this paper are: cond-mat