SPIN STRUCTURE OF THE QUARK-QUARK CONFINING INTERACTION AND THE MASS-SPECTRA OF BOUND QUARK-ANTIQUARK SYSTEMS IN THE FRAMEWORK OF THE SALPETER EQUATION

The mass spectrum of bound quark-antiquark systems is calculated in the framework of the Salpeter equation with the spin structure xgamma1(0)gamma2(0) + (1 - x) I of the confinement part of the quark-quark interaction potential. It is shown that for the case of heavy quarks the results practically do not depend on the value of the mixing parameter x. As to the case of light quarks, the solutions of the Salpeter equation exist only if 0.5 less-than-or-equal-to x less-than-or-equal-to 1, but the mass spectrum does not depend very much on the values of x out of this interval.