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arXiv · 1706.06003

Narrow exotic tetraquark mesons in large-$N_c$ QCD

Wolfgang Lucha·Dmitri Melikhov·Hagop Sazdjian
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Abstract

Discussing four-point Green functions of bilinear quark currents in large-$N_c$ QCD, we formulate rigorous criteria for selecting diagrams appropriate for the analysis of potential tetraquark poles. We find that both flavor-exotic and cryptoexotic (i.e., flavor-nonexotic) tetraquarks, if such poles exist, have a width of order $O(1/N_c^2)$, so they are parametrically narrower compared to the ordinary $\bar qq$ mesons, which have a width of order $O(1/N_c)$. Moreover, for flavor-exotic states, the consistency of the large-$N_c$ behavior of "direct" and "recombination" Green functions requires two narrow flavor-exotic states, each coupling dominantly to one specific meson-meson channel.

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Wolfgang Lucha, Dmitri Melikhov, Hagop Sazdjian. 2017-06-19. Narrow exotic tetraquark mesons in large-$N_c$ QCD. https://doi.org/10.1103/physrevd.96.014022

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