Four-Quark States and Nucleon-Antinucleon Annihilation within the Quark Model with Instanton Induced Interaction

Abstract

The spectrum of $q^2{\bar{q}}^2,J^p=0^{+},2^{+}$ mesons is discussed. We have shown that due to instanton - induced forces the physical states are strong mixtures of the $S{U}_f(3)$ group basis states. The cross-sections for annihilation of the $N\bar{N}$ system into $(q^2{\bar{q}}^2)(q\bar{q})$ mesons are obtained. The $a_0(980)$ meson is considered as $q^2{\bar{q}}^2$ meson consisting of $9_f$ and $36_f$ plets. The branchings are also predicted for the cross-sections for production of the $a_0(980)$ and tensor $q^2{\bar{q}}^2$ mesons in $N\bar{N}$ annihilation.

Comments: 28 pages, latex, 4 figures (one figure is available by request)