π±−pElastic Scattering at 31.4 MeV

Abstract

Five new measurements of ${\pi }^{-}+p$ and three of ${\pi }^{+}+p$ elastic differential cross sections, extend the angular range and the accuracy of the data near 30 MeV. These data, combined with the previous measurements at this energy, provide a significant improvement in the accuracy of $s$- and nonresonant $p$-wave phase shifts. A phase-shift analysis yields four solutions, two of which are inconsistent with photoproduction measurements near threshold. One of the remaining two is preferred on the basis of a considerably more likely fit to recent charge-exchange measurements at the same energy. Assuming $f=0.0878\mathrm{}$; ${\alpha }_1=0.087\mathrm{}\pm 0.009$; ${\alpha }_{11}=0.051\mathrm{}\pm 0.008$; ${\alpha }_{13}=-0.043\mathrm{}\pm 0.004$; ${\alpha }_{31}=-0.008\mathrm{}\pm 0.002$; ${\alpha }_3=-0.066\mathrm{}\pm 0.001$.