[en] Experimental data on πN scattering in the elastic energy region w ≤ 1.45 GeV are analyzed within the K-matrix approach with effective lagrangians. The charge splitting in δ₃₃⁺⁺ and δ₃₃⁰ phases obtained in the phase-shift analisys is studed. It is shown that the change in the sign in the energy dependence of the phase difference can be obtained with different form factors of the Δ⁺⁺ and Δ⁰ only. This means that πNΔ⁺⁺ and πNΔ⁰ interactions have a different range. The underlying nature of the observed phenomena is discussed.

[en] We report the first measurements of the total cross section of the reaction K^-p→Σ⁰γ at eight beam momenta from 514 to 750 MeV/c. The data were obtained at the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory using the Crystal Ball detector consisting of 672 NaI crystals. All charged particles were vetoed by a barrel of plastic scintillators, resulting in a study of only the neutral decays of the Σ⁰. The prompt photon and the photons from the decay products of Σ⁰ were detected for each reconstructed event; the neutron was also detected in a small fraction of the events

[en] The reaction K^-p→Σ⁰π⁰→ neutrals was studied with the Crystal Ball detector at the BNL Alternating Gradient Synchrotron for beam momenta between 514 and 750 MeV/c. The photons from Σ⁰ and π⁰ decays were detected, as well as the neutron in a small fraction of the events. The differential cross section and the Σ⁰ polarization are reported at eight momenta and nearly the full angular range. Total cross sections are derived from Legendre polynomial fits to the data. The measurements presented are of considerably higher precision than previous results