Effects of the Resonance Scattering Amplitude in Nucleon-Antinucleon Reactions

We investigate effects of direct channel resonances for pp elastic and charge exchange scatterings at intermediate energies. In our approach for the resonance amplitude, we take into consideration the effect of the phase shift caused by the background amplitude. Among five independent helicity amplitudes, the resonance amplitude with the Regge recurrence of B resonance shows the dip-bump behavior at the desired position of the scattering angle in the differential cross section of pp elastic scattering. The amplitude with several infinite series of resonance level of the Chew-Frautschi polt reproduces the energy dependence of the secondary maximum of the differential cross section up to 6 GeV/c. We estimate the real to imaginary ratio of the scattering amplitudes to be negative and very small at t=0. We also calculate the differential cross section for pp charge exchange scattering in terms of the resonance amplitude with the same parameters in the case of pp elastic scattering. From the calculation of the polarization parameter, we determine the contribution of the helicity single flip amplitude φ5.