Speaker
Dmitri Melikhov
(HEPHY)
Description
Discussing four-point Green functions of bilinear quark currents in large-Nc 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/Nc²), so they are parametrically narrower compared to the ordinary qq mesons, which have a width of order O(1/Nc). Moreover, for flavor-exotic states, the consistency of the large-Nc behavior of “direct” and “recombination” Green functions requires two narrow flavor-exotic states, each coupling dominantly to one specific meson-meson channel.
Authors
Wolfgang Lucha
(Austrian Academy of Sciences)
Dmitri Melikhov
(HEPHY)
Hagop Sazdjian
(University Paris-Sud)