Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Bethe-Salpeter Amplitudes and Density Correlations for Mesons with
  Wilson Fermions   We present an investigation of various gauge invariant definitions of the
$q\bar q$ Bethe-Salpeter (BS) amplitude for mesons in lattice QCD, and compare
them to the Coulomb and Landau gauge BS amplitudes. We show that the gauge
invariant BS amplitude is considerably broadened by the use of ``fat'' gauge
links (constructed by smearing the links of the original lattice). A
qualitative demonstration of the Lorentz contraction of the pion wavefunction
at non-zero momentum is given. We also calculate density-density correlations
and discuss the limitations in extracting the charge radius of the pion from
these observables. Lastly, the polarization dependence of the BS amplitude for
the $\rho$ meson is exhibited, and we extract the relative admixture of $l=0$
and $l=2$ states showing that simple hydrogen-like wavefunctions provide a good
fit.

27
The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
6
The categories of this paper are: astro-ph
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
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The categories of this paper are: eess
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The categories of this paper are: stat
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The categories of this paper are: bayes-an
1
The categories of this paper are: cs
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The categories of this paper are: dg-ga
4
The categories of this paper are: cond-mat
10
The categories of this paper are: q-bio
29
The categories of this paper are: funct-an