Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The $I=1$ pion-pion scattering amplitude and timelike pion form factor
  from $N_{\rm f} = 2+1$ lattice QCD   The elastic $I=1$ $p$-wave $\pi\pi$ scattering amplitude is calculated
together with the isovector timelike pion form factor using lattice QCD with
$N_{\rm f}=2+1$ dynamical quark flavors. Wilson clover ensembles generated by
the Coordinated Lattice Simulations (CLS) initiative are employed at four
lattice spacings down to $a = 0.05\,\mathrm{fm}$, several pion masses down to
$m_{\pi} = 200\,\mathrm{MeV}$, and spatial volumes of extent $L =
3.1-5.5\,\mathrm{fm}$. The set of measurements on these ensembles, which is
publicly available, enables an investigation of systematic errors due to the
finite lattice spacing and spatial volume. The $\pi\pi$ scattering amplitude is
fit on each ensemble by a Breit-Wigner resonance lineshape, while the form
factor is described better by a thrice-subtracted dispersion relation than the
Gounaris-Sakurai parametrization.

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The categories of this paper are: mtrl-th
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The categories of this paper are: supr-con
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The categories of this paper are: chem-ph
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The categories of this paper are: q-bio
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The categories of this paper are: patt-sol
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The categories of this paper are: chao-dyn
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The categories of this paper are: stat
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The categories of this paper are: comp-gas
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The categories of this paper are: physics
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The categories of this paper are: adap-org
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The categories of this paper are: acc-phys
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The categories of this paper are: eess
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The categories of this paper are: astro-ph
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The categories of this paper are: econ
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The categories of this paper are: cond-mat
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The categories of this paper are: cmp-lg