QCD STRING IN THE BARYON

The QCD motivated constituent string model is extended to consider the baryon. The system of three quarks propagating in a confining backgro und field is studied in the Wilson loop approach, and the effective ac tion is obtained. The resulting Lagrangian at large interquark distanc es corresponds to the Mercedes Bent string configuration. Under the as sumption that quarks are sufficiently heavy to allow the adiabatic sep aration of quark and string-junction motions, the use of hyperspherica l expansion for the quark subsystem makes it possible to write and sol ve the classical equation of motion for the junction. The motion of th e junction is quantized, and it is shown that the effective ''swelling '' of the baryon in relation to the standard potential picture occurs as the result of taking these modes into account. Effects associated w ith a finite pluon-correlation length, which do not affect excited sta tes, but which appear to be substantial for the baryon ground state, r educing the ''swelling'' considerably and leaving room to the short-ra nge Coulomb force in the three-quark system, are discussed.