Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Endpoint singularities in unintegrated parton distributions   We examine the singular behavior from the endpoint region x -> 1 in parton
distributions unintegrated in both longitudinal and transverse momenta. We
identify and regularize the singularities by using the subtraction method, and
compare this with the cut-off regularization method. The counterterms for the
distributions with subtractive regularization are given in coordinate space by
compact all-order expressions in terms of eikonal-line operators. We carry out
an explicit calculation at one loop for the unintegrated quark distribution. We
discuss the relation of the unintegrated parton distributions in subtractive
regularization with the ordinary parton distributions.

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The categories of this paper are: math
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The categories of this paper are: patt-sol
30
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: hep-th
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The categories of this paper are: astro-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: dg-ga
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The categories of this paper are: acc-phys
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The categories of this paper are: solv-int
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The categories of this paper are: eess
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The categories of this paper are: hep-ex
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The categories of this paper are: alg-geom
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The categories of this paper are: adap-org
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The categories of this paper are: cs
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The categories of this paper are: ao-sci