Measurement of the spin-rotation parameters A and R for ${\pi }^{+}$p→${\pi }^{+}$p and ${\pi }^{\mathrm{-}}$p→${\pi }^{\mathrm{-}}$p scattering from 471 to 625 MeV/c

The spin-rotation parameters A and R for ${\pi }^{+}$p and ${\pi }^{\mathrm{-}}$p elastic scattering have been measured at pion momenta from 471 to 625 MeV/c using a frozen spin target polarized in the scattering plane and a recoil-proton polarimeter. Our results show that the major features of the recent πN partial-wave analyses (PWA’s) are correct. This is the first time such confirmation has been possible. Some deviations outside the errors indicate the need for a new round of PWA’s.