Coupled channel analysis of pp→π0π0η, π0ηη and K+K-π0 at 900 MeV/c and of ππ-scattering data: The Crystal Barrel Collaboration

A partial wave analysis of antiproton-proton annihilation data in flight at 900 MeV/c into pi 0 pi 0 eta, pi 0 eta eta and K+K-pi 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 D-wave as well as I = 1 P-wave data utilizing the K-matrix approach. Analyticity is treated using Chew-Mandelstam functions. In the fit all ingredients of the K-matrix, 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=1-JPC=1-+pi 1-wave 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+K-pi 0 have been studied in detail. The differential production cross section for the two reactions and the spin-density-matrix elements for the phi (1020) and K(892)+/- have been extracted. No spin-alignment is observed for both vector mesons. The spin density matrix elements have been also determined for the spin exotic wave.