The impact of ${\mathbf{K}}^{+}\mathbf{\Lambda }$ photoproduction on the resonance spectrum

Abstract

The Jülich-Bonn coupled-channel framework is extended to $K^{+}\Lambda$ photoproduction. The spectrum of nucleon and $\Delta$ resonances is extracted from simultaneous fits to several pion-induced reactions in addition to pion, eta and $K^{+}\Lambda$ photoproduction off the proton. More than 40,000 data points up to a center-of-mass energy of E$\sim$2.3 GeV including recently measured double-polarization observables are analyzed. The influence of the $\gamma p\to K^{+}\Lambda$ channel on the extracted resonance parameters and the appearance of states not seen in other channels is investigated. The Jülich-Bonn model includes effective three-body channels and guarantees unitarity and analyticity, which is a prerequisite for a reliable determination of the resonance spectrum in terms of poles and residues.

Comments: 21 pages, 11 figures. Minor modifications, additional information in the appendix. Accepted for publication in Eur. Phys. J. A