Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Update of the pi N --> eta N and eta N --> eta N partial-wave amplitudes   A three-channel, multi-resonance, unitary model developed in 1995 is used to
determine the $\pi N \rightarrow \eta N$ and $\eta N \rightarrow \eta N$
amplitudes using as input the latest data for the dominant $S_{11}$ $\pi N$
elastic scattering partial wave following suggestions of Prof. G. H\"{o}hler.
The sign error in the numerical evaluation of the dispersion integral in the
original publication is eliminated. The remaining weighted data set for the
$\pi N \rightarrow \eta N$ total and differential cross sections is used as in
the original publication. The correction of the numerical error influences the
$\eta N$ cusp effect and improves the quality of the fit to the input data.
However, our new result for the $\eta N$ scattering length, $a_{\eta N }=
(0.717 \pm 0.030) + i (0.263 \pm 0.025)$ fm, is a sole consequence of the
correction of the $S_{11}$ input and suggests that the $\eta d$ system is
unbound or loosely bound.

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The categories of this paper are: econ
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The categories of this paper are: comp-gas
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The categories of this paper are: nucl-ex
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The categories of this paper are: physics
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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: chao-dyn
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The categories of this paper are: nlin
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The categories of this paper are: supr-con
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-lat
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The categories of this paper are: q-fin
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The categories of this paper are: math
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The categories of this paper are: stat
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The categories of this paper are: cmp-lg
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The categories of this paper are: patt-sol