Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Neutral pion photoproduction on deuterium in baryon chiral perturbation
  theory to order q^4   Threshold neutral pion photoproduction on the deuteron is studied in the
framework of baryon chiral perturbation theory beyond next-to--leading order in
the chiral expansion. To fourth order in small momenta, the amplitude is finite
and a sum of two- and three-body interactions with no undetermined parameters.
With accurate theoretical and experimental input from the single nucleon sector
for the proton amplitude, we investigate the sensitivity of the threshold cross
section to the elementary $\gamma n \to \pi^0 n$ amplitude. A precise
measurement of the threshold cross section for $\gamma d \to \pi^0 d$ is called
for.

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The categories of this paper are: patt-sol
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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: bayes-an
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The categories of this paper are: eess
36
The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio
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The categories of this paper are: solv-int
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The categories of this paper are: q-alg
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The categories of this paper are: hep-th
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The categories of this paper are: math
9
The categories of this paper are: nlin
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The categories of this paper are: alg-geom
6
The categories of this paper are: astro-ph
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The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con