Dispersion theoretic analysis of the proton-proton helicity amplitudes at t = 0

Abstract

A dispersion analysis of all three forward proton-proton amplitudes is performed, using the data for total cross sections in pure spin states and phase shifts in the domain of predominantly elastic scattering. We find that the high-energy behaviour of φ 2 is dominated by exchanges with isospin 1, and that a single unnatural parity exchange (e.g. A 1) is insufficient to reproduce the high-energy behavior of φ 1 − φ 3. Knowingthe forward amplitudes, we are able to predict a great variety of observables and to compare the predictions with existing experimental data. Furthermore the amplitudes show two resonance-like structures which are consistent with Breit-Wigner behaviour. One of the structures appears in a spin-singlet state with mass 2390 MeV and a width of 100 MeV. The other structure occurs in an uncoupled triplet state, probably in the 3F 3 state, with a mass of 2320 MeV ( Γ = 290 MeV).