Updated determination of $N^{\ast }$ resonance parameters using a unitary, multichannel formalism

Abstract

Results are presented for an updated multichannel energy-dependent partial-wave analysis of $\pi N$ scattering. Our earlier work incorporated single-energy amplitudes for $\pi N\to \pi N$, $\gamma N\to \pi N$, $\pi N\to \pi \pi N$, $\pi N\to \eta N$, and $\pi N\to K\Lambda$. The present work incorporates new single-energy solutions for $\gamma p\to \eta p$ up to a c.m.\ energy of 1990~MeV, $\gamma p\to K^{+}\Lambda$ up to a c.m.\ energy of 2230~MeV, and $\gamma n\to \eta n$ up to a c.m.\ energy of 1885~MeV, as well as updated single-energy solutions for $\pi N\to \eta N$, $\pi N\to K\Lambda$, and $\gamma N\to \pi N$. In this paper, we present and discuss the resonance parameters obtained from a combined fit of all these single-energy amplitudes. Our determined energy-dependent amplitudes provide an excellent description of the corresponding measured observables.

41 pages, 26 figures