Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: O(a) improved lattice QCD   We review the O(a) improvement of lattice QCD with special emphasis on the
motivation for performing the improvement programme non-perturbatively and the
general concepts of on-shell improvement. The present status of the
calculations of various improvement coefficients (perturbative and
non-perturbative) is reviewed, as well as the computation of the isospin
current normalization constants $Z_A$ and $Z_V$. We comment on recent results
for hadronic observables obtained in the improved theory.

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The categories of this paper are: chem-ph
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The categories of this paper are: nlin
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The categories of this paper are: bayes-an
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The categories of this paper are: plasm-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: supr-con
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-ex
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The categories of this paper are: acc-phys
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The categories of this paper are: econ
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The categories of this paper are: q-fin
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The categories of this paper are: chao-dyn
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-alg
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The categories of this paper are: mtrl-th