Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: NLO perturbative QCD predictions for gamma gamma -> M+ M- (M=pi,K)   We report the first complete leading-twist next-to-leading-order perturbative
QCD predictions for the two-photon exclusive channels gamma gamma -> M+ M-
(M=pi,K) at large momentum transfer. The asymptotic distribution amplitude is
utilized as a candidate form for the nonperturbative dynamical input.
Comparison of the obtained results with the existing experimental data does not
provide sufficiently clear evidence to support the applicability of the
hard-scattering approach at currently accessible energies.

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The categories of this paper are: supr-con
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The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
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The categories of this paper are: q-alg
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: nlin
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The categories of this paper are: cmp-lg
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The categories of this paper are: chem-ph
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The categories of this paper are: atom-ph
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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: stat
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The categories of this paper are: acc-phys
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The categories of this paper are: chao-dyn
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The categories of this paper are: comp-gas