Compact Exotic Tetraquark Mesons in Large-$N_c$ QCD

Abstract

We embark on systematic explorations of the behaviour of tetraquark mesons (colour-singlet bound states of two quarks and two antiquarks) in the (idealized) limit of a large number $N_c$ of colour degrees of freedom of quantum chromodynamics. Considering the scattering of two ordinary mesons into two ordinary mesons, we start off with formulating a set of selection criteria that should enable us to unambiguously single out precisely those contributions to all encountered scattering amplitudes that potentially will develop tetraquark poles. Assuming that tetraquark mesons do exist and, if so, emerge in the contributions compatible with our criteria at largest admissible order of $N_c$, we deduce, for the categories of tetraquarks that exhibit either four or only two different open quark flavours, that the decay rates of these tetraquark types are, at least, of order $1/N_c^2$ and that internal consistency requires all the members of the first species to exist pairwise, distinguishable by their favoured two-ordinary-meson decay channels.

8 pages, 5 figures, talk presented at "QUARKS-2018 - XXth International Seminar on High Energy Physics" (27 May - 2 June 2018, Valday, Russia)

References in corpus (7)

• Are There Tetraquarks at Large $N_c$ in QCD(F)?
• Narrow exotic tetraquark mesons in large-$N_c$ QCD
• Tetraquarks in the 1/N expansion and meson-meson resonances
• Tetraquark and two-meson states at large $N_{\mathrm{c}}$
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Cited by in corpus (1)

• Compact Flavour-Exotic Tetraquarks in Large-$N_{\mathrm{c}}$ QCD - To Be or Not to Be?