Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Excited $[{\bf 70, \ell^+}]$ baryons in large $N_c$ QCD   The masses of the positive parity $[{\bf 70},0^+]$ and $[{\bf 70},2^+]$
non-strange baryons are calculated in large $N_c$ QCD by considering the most
dominant operators in an $1/N_c$ expansion. The approach is based on the
introduction of an excited core, obtained after the last particle (an excited
quark) has been removed. Configuration mixing is neglected, for simplicity.
Although being a sub-leading $1/N_c$ order, we find that the spin-spin
interaction plays a dominant role in describing the data. The role of $N_c^ 0$
operators is also pointed out. We show how the contribution of the linear term
in $N_c$, of the spin-spin and spin-orbit terms vary with the excitation
energy.

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The categories of this paper are: dg-ga
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The categories of this paper are: patt-sol
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The categories of this paper are: cmp-lg
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The categories of this paper are: acc-phys
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The categories of this paper are: math
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The categories of this paper are: econ
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The categories of this paper are: cs
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The categories of this paper are: mtrl-th
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The categories of this paper are: cond-mat
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The categories of this paper are: bayes-an
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The categories of this paper are: solv-int
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The categories of this paper are: chem-ph
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The categories of this paper are: adap-org
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The categories of this paper are: nlin
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The categories of this paper are: math-ph
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The categories of this paper are: funct-an