0000000000416594
AUTHOR
Teresa Fernández Caramés
piB B-88 and sigmaB B-88 couplings from a chiral quark potential model
From an SU(2)⊗SU(2) chiral quark potential model incorporating spontaneous chiral symmetry breaking the asymptotic π and σ exchange pieces of the NN potential are generated. From them the πNN and σNN coupling constants can be extracted. The generalization to SU(3)⊗SU(3) allows for a determination of πB8B8 and σB8B8 coupling constants according to exact SU(3) hadron symmetry. The implementation of the values of the couplings at Q2=0 provided by QCD sum rules and/or phenomenology makes also feasible the extraction of the meson-baryon-baryon form factors. In this manner a quite complete knowledge of the couplings may be attained.
Diquark-diquark correlations in the S-1(0)Lambda Lambda potential
We derive a ΛΛ potential from a chiral constituent quark model that has been successful in describing one, two and three nonstrange baryon systems. The resulting interaction at low energy is attractive at all distances due to the σ exchange term. The attraction allows for a slightly bound state just below the ΛΛ threshold. No short-range repulsive core is found. We extract the diquark-diquark contribution that turns out to be the most attractive and probable at small distances. At large distances the asymptotic behavior of the ΛΛ interaction provides a prediction for the σΛΛ coupling constant.
Too many X's, Y's and Z's?
Heavy meson spectroscopy above open flavor thresholds has become a challenge both from the experimental and theoretical points of view. Experimentally, several signals have been interpreted as meson resonances with unusual properties; theoretically, such signals may be identified with meson-meson molecules or compact multiquark structures. We analyze the influence of thresholds on heavy meson spectroscopy comparing different flavor sectors and quantum numbers. The validity of a quark-model picture above open-flavor thresholds would severely restrict the number of channels that may lodge multiquark structures as meson-meson molecules.