Phase shift analysis of NN scattering

A phase shift analysis is reported incorporating the world data on NN observables from 1 GeV/c. In I, we summarize I=1 phase shift solutions at 12 energy points from 430-800 MeV. The solutions are well determined up to 585 MeV and fairly well determined above 625 MeV. Half-looping behavior on the Argand plane is found in the 1D2 and 3F3 partial waves. Structure in the 3P2 amplitude is analyzed briefly in relation to experimental data. In II, I=0 phase shift solutions are obtained at 8 energy points from 430-800 MeV. Two analyses are performed with I=0 absorption parameters ηLJ0's fixed to 1 (no absorption) and with ηLJ0's floated. The results are that I=0 absorptions are important, in particular at 625 MeV and at 645 MeV. Solutions with absorptions reveal a narrow resonance structure in the 1P1 partial wave. In III, a Breit-Wigner analysis of this resonance is performed. We obtain the resonance parameters as JP=1-, M=2168 MeV/c2, Γ/2=12.5 MeV and Γel/Γ=0.2. The np reaction cross section with I=0, σr0, is predicted to have a sharp peak at 625 MeV in Tlab, in agreement with the σr0-data by Dunaitsev and Prokoshkin. In IV, we study S-matrix poles in NΔ scattering. The NΔ 5S2 phase shift reported by Shypit et al. is explained on the basis of the S-matrix pole of unstable bound state type (M=2150 MeV, JP=2+), by taking into account instability of the Δ, NN final state interaction for NΔ→npπ+, factor i in ΔNπ-interaction. This pole explains also the 1D2 phase parameters for pp→pp around 2150 MeV in √s. The phase for pp(3P1)→NS(3S1) is discussed briefly. If the NN FSI is subtracted, we have δNS(3S1)∼90deg at an energy below ∼490 MeV (M∼1880-2110 MeV, JP=1-). (author)