Measurement of the η–η′ mixing angle in π − and K − beams with the GAMS-4π Spectrometer
European Physical Journal C: Particles and Fields
The results of mixing angle measurement for η', η mesons generated in charge exchange reactions with π^- and K^- beams are preseneted. When the η', η mesons are described in nonstrange(NS)--strange(S) quark basis the π^- and K^- beams allow to study |η_q> and |η_s> parts of the meson wave function. The cross section ratio at t'=0 (GeV/c)^2 in the π^- beam is R_π(η'/η)= 0.56 ± 0.04, results in mixing angle ϕ_P = (36.8 ± 1.)^o . For K^- beam the ratio is R_K(η'/η)= 1.30 ± 0.16. It was found that
... luonium content in η' is sin^2ψ_G= 0.15 ± 0.06. The experiment was carried out with GAMS-4π Setup.