LOW-LYING MESON SPECTROSCOPY AND CONFINEMENT

The paper is devoted to the construction of low-energy quark-scattering amplitudes. The amplitudes of dressed quarks qq --> qq and qqBAR --> qqBAR (q = u, d, s) are calculated in the framework of the dispersion N/D method with the help of the iteration bootstrap procedure including two types of point-like input interactions, namely the four-fermion interaction with quantum numbers of the gluon and four-fermion interaction induced by instantons (the exchanges of white states with J(P) = 0+/-). The mass values of the lowest mesons (J(P) = 0-, 1-, 0+) and their quark content are obtained. In the colour meson channel a bound state was found which corresponds to the constituent gluon with the mass M(G) = 0.67 GeV. The qq-amplitudes in the colour state 3BAR have the diquark levels with J(P) = 0+ and the masses m(ud) = 0.72 GeV and m(us) = m(ds) = 0.86 GeV. The interaction of dressed quarks appeared to be an effectively short-range one. The calculated amplitudes satisfy the Okubo-Zweig-Iisuka rule. The creation of mesons (pion included) is mainly due to the gluon exchange. The mesons with heavy quarks (c and b) are considered also, using the calculated forces. We discuss the possibility of constructing the amplitudes which take into account the quark confinement.