Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: All order alpha'-expansion of superstring trees from the Drinfeld
  associator   We derive a recursive formula for the alpha'-expansion of superstring tree
amplitudes involving any number N of massless open string states. String
corrections to Yang-Mills field theory are shown to enter through the Drinfeld
associator, a generating series for multiple zeta values. Our results apply for
any number of spacetime dimensions or supersymmetries and chosen helicity
configurations.

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The categories of this paper are: cond-mat
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The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
0
The categories of this paper are: hep-ph
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The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
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The categories of this paper are: q-fin
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The categories of this paper are: patt-sol
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The categories of this paper are: solv-int
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The categories of this paper are: physics
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The categories of this paper are: math-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-ex
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The categories of this paper are: nucl-ex