We discuss the stability of multiquark systems within the recent model of Glozman et al. where the chromomagnetic hyperfine interaction is replaced by pseudoscalar-meson exchange contributions. We find that such an interaction binds a heavy tetraquark systems QQqq (Q = c, b and q = u, d) by 0.2 − 0.4 GeV. This is at variance with results of previous models where ccqq is unstable.1
Within the chiral constituent quark model of Glozman and Riska, we discuss the stability of heavy pentaquarks, i.e. hadrons containing four light quarks and a heavy antiquark. The spin-dependent part of the Hamiltonian is dominated by the short-range part of the Goldstone-boson-exchange interaction.We find that these systems are not bound, having an energy above the lowest dissociation threshold into a baryon and a meson.The question of the existence of hadrons other than mesons qq and baryons q 3 remains open. Multiquark states as tetraquarks q 2q2 , pentaquarks q 4q or hexaquarks q 6 , could exist in * Supported by the EU program ERBFMBICT 950427 1
Recently it has been argued that a three-body color confinement interaction can affect the stability condition of a three-quark system and the spectrum of a tetraquark described by any constituent quark model. Here we discuss the role of a three-body color confinement interaction in a simple quark model and present some of its implications for the spectra of baryons, tetraquarks and six-quark systems.
We study the instabilities of quark matter in the framework of a gener- However, except at densities below about a quarter of that of nuclear matter, we find that scalar diquark formation is energetically favored. This raises the question of whether a realistic phase diagram of baryonic matter can be obtained from any model which does not incorporate color confinement.
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