Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Parton Distributions: Progress and Challenges   We briefly discuss recent research on the spin-averaged parton densities of
the proton, focusing on some aspects relevant to hard processes at the LHC.
Specifically, after recalling the basic framework and the need for higher-order
calculations, we address the evolution equations governing the scale dependence
of the parton distributions and their solution, schemes for initial conditions
and the inclusion of heavy quarks, recent progress on fits to data, and future
high-precision constraints from LHC measurements.

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The categories of this paper are: patt-sol
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The categories of this paper are: quant-ph
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The categories of this paper are: math-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: q-bio
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The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
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The categories of this paper are: supr-con
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The categories of this paper are: mtrl-th
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The categories of this paper are: adap-org
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The categories of this paper are: dg-ga
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The categories of this paper are: solv-int