Albrecht, M.; Amsler, C.; Duennweber, W.; Faessler, M. A.; Heinsius, F. H.; Koch, H.; Kopf, B.; Kurilla, U.; Meyer, C. A.; Peters, K.; Pychy, J.; Qin, X.; Steinke, M.; Wiedner, U.
(2020):
Coupled channel analysis of p¯p → π0π0η, π0ηη and K+K−π0 at 900 MeV/c and of ππscattering data: The Crystal Barrel Collaboration.
In: European Physical Journal C, Vol. 80, No. 5

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Abstract
A partial wave analysis of antiprotonproton annihilation data in flight at 900 MeV/c into pi 0 pi 0 eta, pi 0 eta eta and K+Kpi 0 is presented. The data were taken at LEAR by the Crystal Barrel experiment in 1996. The three channels have been coupled together with pi pi scattering isospin I = 0 S and Dwave as well as I = 1 Pwave data utilizing the Kmatrix approach. Analyticity is treated using ChewMandelstam functions. In the fit all ingredients of the Kmatrix, including resonance masses and widths, were treated as free parameters. In spite of the large number of parameters, the fit results are in the ballpark of the values published by the Particle Data Group. In the channel pi 0 pi 0 eta a significant contribution of the spin exotic IG=1JPC=1+pi 1wave with a coupling to pi 0 eta is observed. Furthermore the contributions of phi (1020)pi 0 and K(892)+/ K /+ in the channel K+Kpi 0 have been studied in detail. The differential production cross section for the two reactions and the spindensitymatrix elements for the phi (1020) and K(892)+/ have been extracted. No spinalignment is observed for both vector mesons. The spin density matrix elements have been also determined for the spin exotic wave.