We present results from a comprehensive partial-wave analysis of ${\pi }^{\pm }p$ elastic scattering and charge-exchange data, covering the region from threshold to $2.1\text{GeV}$ in the lab pion kinetic energy, employing a coupled-channel formalism to simultaneously fit ${\pi }^{-}p\to \eta n$ data to $0.8\text{GeV}$. Our main result, solution FA02, utilizes a complete set of forward and fixed-$t$ dispersion relation constraints, from threshold to $1\text{GeV}$, and from $t=0$ to $-0.4{(\text{GeV}∕c)}^2$, applied to the $\pi N$ elastic amplitude. A large number of systematic checks have been performed, including fits with no charge-exchange data and other database changes, fits with few or no dispersion relation constraints, and changes to the Coulomb correction scheme. We have also reexamined methods used to extract Breit-Wigner resonance parameters. The quality of fit to both data and dispersion relation constraints is superior to our earlier work. The results of these analyses are compared with previous solutions in terms of their resonance spectra and preferred values for couplings and low-energy parameters, including the $\pi NN$ coupling constant.

• Received 26 November 2003

DOI:https://doi.org/10.1103/PhysRevC.69.035213