Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gluonic contribution to $B\to \eta^{(\prime)}$ form factors   We calculate the flavor-singlet contribution to the $B\to\eta^{(\prime)}$
transition form factors from the gluonic content of the $\eta^{(\prime)}$ meson
in the large-recoil region using the perturbative QCD approach. The formulation
for the $\eta$-$\eta'$ mixing in the quark-flavor and singlet-octet schemes is
compared, and employed to determine the chiral enhancement scales associated
with the two-parton twist-3 $\eta^{(\prime)}$ meson distribution amplitudes. It
is found that the gluonic contribution is negligible in the $B\to\eta$ form
factors, and reaches few percents in the $B\to\eta'$ ones. Its impact on the
accommodation of the measured $B\to\eta^{(\prime)} K$ branching ratios in the
perturbative QCD and QCD-improved factorization approaches is elaborated.

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The categories of this paper are: ao-sci
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-bio
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The categories of this paper are: econ
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The categories of this paper are: math
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The categories of this paper are: math-ph
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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: stat
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The categories of this paper are: cs
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The categories of this paper are: solv-int
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The categories of this paper are: quant-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: chao-dyn
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The categories of this paper are: physics