Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: pi pi scattering in a nonlocal Nambu -- Jona-Lasinio model   We consider a nonlocal version of the Nambu and Jona-Lasinio model. The
nonlocality is contained in the quark-antiquark bilinears of the four-quark
vertices as a form factor of the Gaussian type. The model has three parameters
which can be fixed in favour of the values of the pion mass, the pion decay
constant f_pi, and the current quark mass. The pi pi scattering amplitude is
obtained by calculating the quark box and the sigma-pole diagrams, where sigma
is the scalar isoscalar meson. It is shown that this amplitude satisfies the
well-known Weinberg relation. We obtain the s, p, d wave scattering lengths in
all isotopic channels and the s wave slope parameters. The results are in
satisfactory agreement with both phenomenological data and the basic
requirements of low-energy theorems, thus supporting to the form factor used.

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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: eess
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The categories of this paper are: chao-dyn
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The categories of this paper are: mtrl-th
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The categories of this paper are: quant-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: econ
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: funct-an
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The categories of this paper are: nlin
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The categories of this paper are: nucl-th
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The categories of this paper are: comp-gas
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The categories of this paper are: supr-con
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The categories of this paper are: q-bio