THE RHO PARAMETER OF LOW-ENERGY PROTON-ANTIPROTON SCATTERING IN THE P-3(O) QUARK-MODEL

The real-to-imaginary ratio rho of the proton-antiproton forward elast ic scattering amplitude is analyzed in a nucleon-antinucleon (<N(N)ove r bar>) potential model. The annihilation part of the <N(N)over bar> i nteraction is based on a constituent quark model applying the effectiv e P-3(0) quark-antiquark operator together with a planar quark diagram topology. The elastic interaction is the G-parity transform of meson exchange NN interactions as defined by the Bonn and Pan's potentials. The momentum dependence of the rho parameter can be well reproduced fo r p(lab) > 250 MeV/c, but despite strong variations in the parameteriz ation of the annihilation part no pronounced bump structure for rho at low momenta as suggested by experiment can be found.