Comparison of analyzing power predictions forppscattering in the Coulomb-nuclear interference region at 185.4 MeV

Recent measurements of the analyzing power ${\mathit{A}}_{\mathit{y}}$ for elastic proton-proton scattering are compared to predictions of phase-shift analyses and potential models. One measurement is an absolute determination of ${\mathit{A}}_{\mathit{y}}$ at a beam energy of 183.1 MeV. The second measurement is a precise determination of the angular distribution ${\mathit{A}}_{\mathit{y}}$(θ) over the angular range ${\mathrm{\theta }}_{\mathrm{c}.\mathrm{m}.\mathrm{}}$=5.45°–21.36° at a beam energy of 185.4 MeV. At these small angles the interference between the Coulomb and nuclear amplitudes dominates ${\mathit{A}}_{\mathit{y}}$(θ). Potential model calculations without the electromagnetic spin-orbit force fail to reproduce the data. Phase-shift analyses, all of which include some form of the electromagnetic spin-orbit force, tend to have a better overall agreement with the data than the potential models.