Multichannel resonance parametrization ofπNscattering amplitudes

A new manifestly time-reversal invariant and unitary parametrization of $S$-matrix elements is described. The method is simpler than the $K$-matrix approach in that resonance parameters are parametrized directly. The technique is used to extract resonance parameters from partial-wave amplitudes for $\pi N\to \pi N$ and from isobar-model amplitudes for $\pi N\to \pi \pi N$. Resonance parameters obtained from this approach are tabulated and compared to predictions of quark-model calculations and to results of previous work.