Partial-Wave Analysis ofπ−+p→η+n

Abstract

It is shown that by using the nucleon pole and a sum of direct-channel resonances, a reasonable fit to both the differential and total cross sections, for the process ${\ensuremath{\pi}}^{\ensuremath{-}}+p\ensuremath{\rightarrow}\ensuremath{\eta}+n$, is obtained for incident-pion laboratory kinetic energies (${T}_{\ensuremath{\pi}}$) between threshold and 1.3 GeV. Inelastic branching ratios for the $\ensuremath{\eta}n$ channel are predicted with results consistent with experiment. The $\ensuremath{\eta}$-nucleon coupling constant is found to be $\frac{{{g}_{\ensuremath{\pi}\mathrm{NN}}}^{2}}{4\ensuremath{\pi}}\ensuremath{\lesssim}{10}^{\ensuremath{-}4}$. By assuming the spin and parity of the $N(2650)$ to be ${J}^{P}={\frac{11}{2}}^{\ensuremath{-}}$, agreement with the polarization data near the $N(2650)$ is obtained. However, this model can not give a good fit to the differential cross-section data at ${T}_{\ensuremath{\pi}}=2.41 \mathrm{and} 2.93$ GeV.