Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Is the eta Meson a Goldstone Boson?   The decoupling of the eta meson from the nucleon, as recently deduced from
analyzing \bar p p collisions and eta photoproduction off the proton at
threshold, is shown to provide an argument against the octet Goldstone boson
nature of the eta meson. This argument concerns the structure of the strong
isoscalar axial vector current. A vanishing eta-N coupling means a vanishing
contribution of the eta-pole term to the hypercharge nucleon axial vector
current. Therefore, no partial conservation of the latter can be achieved. This
new situation invalidates the octet Goldberger--Treiman relation for the eta-N
coupling constant that is indicative of the octet Goldstone boson nature of the
eta meson. In such a case there is no longer a compelling reason for the
standard belief that the eta meson should be coupled to the hadronic vacuum
through the hypercharge axial vector current. Rather, it will be coupled to it
as any ordinary neutral pseudoscalar meson via the neutral axial vector current
of the electroweak theory. As a result of the suggested universal structure of
the weak and strong neutral axial vector currents the eta meson satisfies the
strange analog of the Goldberger-Treiman relation so that it acquires features
of a strange Goldstone boson. Hence the eta-NN vertex constant appears
proportional to $\Delta s$, the fraction of nucleon spin carried by the strange
quark sea, thus explaining its suppression naturally.

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The categories of this paper are: physics
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The categories of this paper are: chem-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: q-alg
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The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-ex
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-th
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The categories of this paper are: eess
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The categories of this paper are: gr-qc
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The categories of this paper are: quant-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: nlin
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The categories of this paper are: ao-sci
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The categories of this paper are: math
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The categories of this paper are: patt-sol