Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Next-to-Next-to-Leading Order Evolution of Flavour-Singlet
  Fragmentation Functions   We present the third-order contributions to the quark-gluon and gluon-quark
timelike splitting functions for the evolution of fragmentation functions in
perturbative QCD. These quantities have been derived by studying physical
evolution kernels for photon- and Higgs-exchange structure functions in deep
inelastic scattering and their counterparts in semi-inclusive annihilation,
together with constraints from the momentum sum rule and the supersymmetric
limit. For this purpose we have also calculated the second-order coefficient
functions for one-hadron inclusive Higgs decay in the heavy-top limit. A
numerically tolerable uncertainty remains for the quark-gluon splitting
function, which does not affect the endpoint logarithms for small and large
momentum fractions. We briefly discuss these limits and illustrate the
numerical impact of the third-order corrections. Compact and accurate
parametrizations are provided for all third-order timelike splitting functions.

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The categories of this paper are: ao-sci
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The categories of this paper are: physics
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The categories of this paper are: funct-an
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The categories of this paper are: hep-ex
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The categories of this paper are: econ
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The categories of this paper are: eess
10
The categories of this paper are: q-bio
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-th
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The categories of this paper are: alg-geom
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The categories of this paper are: plasm-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: mtrl-th
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The categories of this paper are: nlin
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The categories of this paper are: math
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The categories of this paper are: hep-lat