Bound-state Picture Research Articles

Calculation of the polarization of the recoil proton in ?N-scattering near the inelastic threshold

The polarization of the recoil proton in πN-scattering has been calculated as a function of the scattering angle at the energies 150, 170, 190 MeV. It is shown that this polarization depends sensitively on the πN-scattering phase-shiftP11. Slight changes of the other phase-shifts do not affect the polarization to the same extent. New measurements of the differential cross-section and of the polarization in the process π−+p→π−+p are suggested. They would allow for a new precise phase-shift analysis, which could possibly determine the sign of theP11-phase at the inelastic threshold. This sign is important in connection with the bound-state picture of the nucleon.

Is the nucleon a bound state?

In this paper we deal with the question of whether or not the nucleon is a bound state. It is shown that previous work on this problem is not conclusive. We find, however, a simple criterion which allows for an experimental decision of this question. For the nucleon to be a bound state, thep1/2,1/2 phase has to have a negative sign at the inelastic threshold. A positive phase excludes the bound state picture but allows ap1/2,1/2 resonance to occur.