Measurement of the asymmetry parameter $A$ in ${\pi }^{-}p$ elastic and charge-exchange scattering at pion energies $T_{\pi }=98, 238, 292, \mathrm{and} 310$ MeV

The asymmetry parameter $A$ in ${\pi }^{-}p$ elastic scattering at incident pion laboratory kinetic energies $T_{\pi }$ of 98, 238, and 2922 MeV and in ${\pi }^{-}p$ charge-exchange scattering ${\pi }^{-}p\to {\pi }^{0}n$ at $T_{\pi }=238, 292, \mathrm{and} 310$ MeV have been measured over a wide range of scattering angles (typically from about 60° to 130° c.m.) with a polarized proton target. The data have been used in an energy-independent phase-shift analysis to improve the precision of the pion-nucleon phase shifts, to set new limits on violation of isospin conservation in the pion-nucleon $S$ wave, and to confirm significant charge dependence in the $P_{\frac{3}{2}}$ wave.