Coupled-channel analysis ofKΣproduction on the nucleon up to 2.0 GeV

Abstract

A coupled-channel effective Lagrangian model respecting unitary and gauge invariance is applied to the combined analysis of (π, γ )N → K reactions for center-of-mass energies up to 2 GeV. The recent photoproduction data obtained by the CLAS, CBELSA, LEPS, and GRAAL groups are included into our calculations with the aim to extract the resonance couplings to the K state. Both resonances and background contributions are found to be important to reproduce correct shapes of the angular distributions and polarization observables. Our description of the data is of good quality. The extracted properties of isospin I = 3/2 resonances are discussed in detail while the I = 1/2 resonances are largely determined by the nonstrangeness channels.

2πproduction in the Giessen coupled-channels model

“…Since the πN → 2πN reaction could account for up to 50% of the πN inelasticity this production channel had been included into the GiM calculations [1][2][3][4][5][6][7][8][9]. However due to the complexity of the problem the 2πN final state has been treated in a simplified way where only resonance decays into a 'generic' 2πN final state were allowed.…”

Coupled channels approach to photo-meson production on the nucleon

“…5, illustrating the quality of the description on the example of π − p → K 0 Σ 0 reaction. The complete set of results, including partial wave cross sections, angular distributions of cross sections and polarization observables for the full set of KΣ exit channels are found in [6].…”

“…In addition, such production reactions are also an appropriate tool to identify excited states N * of the nucleon which decay preferentially into hyperon-kaon channels, thus adding to solve the problem of missing resonances. In [6] we have analysed the latest CLAS-, CBELSA-data sets and re-analysed the earlier SAPHIR-data on photoproduction of kaons on the nucleon. The Giessen model was used, describing meson production on the nucleon by a coupled channels K-matrix approach including meson production by photoproduction and pion-induced reactions as initial channels.…”

“…The central aim was to extract the resonance couplings to the KΣ state. In [6] the Giessen model was used to reanalyze newly released data from various experimental groups for KΣ production on the nucleon. Both s-channel resonances and t,u-channel background contributions are found to be important for an accurate description of angular distributions and polarization observables, assuring a high quality description of the data.…”

“…The Giessen coupled-channel model (GiM) has been developed for a combined analysis of pion-and photon-induced reactions e-mail: horst.lenske@physik.uni-giessen.de on the nucleon, (π/γ) + N, for extracting properties of nucleon resonances. The applications range from investigations of the elastic and inelastic πN and πN * channels [1] to ωN [2], ηN [3,4] production as well as the strangeness channels KΛ [5] and KΣ [6]. The 2πN channels were investigated recently in [7].…”