Soft π−p and pp elastic scattering in the energy range 30 to 345 GeV

Abstract

Differential cross sections for π −p and pp elastic scattering have been measured at incident momenta ranging from 30 to 345 GeV and in the t range 0.002 (GeV/ c) 2 ⩽ | t| ⩽ 0.04 (GeV/ c) 2. From the analysis of the data, the ratio ϱ ( t = 0) of the real to the imaginary parts of the forward scattering amplitude was determined together with the logarithmic slope b of the diffraction cone. The results on the real parts confirm the validity of the forward dispersion relations at high energies. Using the dispersion relations, it was shown that the experimental data on ϱ π−p( t = 0) require a continuous rise of the total πp cross sections, at least up to the energy of 2000 GeV, thus revealing a close similarity in high-energy behaviour of πp and pp interactions. The results on the slope parameters from this experiment together with the analysis of the available world data demonstrate that the existing experimental data are consistent with the hypothesis of a universal shrinkage of the hadronic diffraction cone at high energies. The value of the asymptotic shrinkage parameter α p ′ was found to be independent of the kind of the incident hadron and of the momentum transfer in the t range | t| ⩽ 0.2 (GeV/ c) 2 : 2 α p ′ = ± 3 (GeV/ c) −2 .