Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nucleon-Nucleon Effective Field Theory at NNLO: Radiation Pions and 1S0
  Phase Shift   Low energy phenomena involving two nucleons can be successfully described
using effective field theory. Because of the relatively large expansion
parameter, it is only at next-to-next-to-leading order (NNLO) where one can
expect to see agreement with experiment at the few percent level. The first
part of this talk will focus on radiation pion effects, which first appear at
NNLO. The power counting for radiation pions is simple for center of mass
momentum p~\sqrt{M m_pi}=Q_r, the threshold for pion production. We explain how
graphs calculated with the Q_r power counting scale for p~m_\pi. The Q_r^3
radiation pion contributions to nucleon-nucleon scattering are suppressed by
inverse powers of the S-wave scattering lengths. However, we point out that
order Q_r^4 radiation contributions might give a NNLO contribution for p~m_pi.
In the second part of the talk, results for the potential pion and contact
interaction part of the NNLO 1S0 phase shift are presented. We emphasize the
importance of eliminating spurious poles in the expression for the amplitude at
each order in the perturbative expansion. Doing this leaves a total of three
free parameters at NNLO. We obtain a good fit to the 1S0 phase shift.

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The categories of this paper are: eess
27
The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
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The categories of this paper are: astro-ph
7
The categories of this paper are: hep-th
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The categories of this paper are: math-ph
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
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The categories of this paper are: stat
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The categories of this paper are: alg-geom
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The categories of this paper are: acc-phys
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The categories of this paper are: q-bio
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The categories of this paper are: chao-dyn
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The categories of this paper are: quant-ph
4
The categories of this paper are: cond-mat