Study of the K^+ K^- π^+ π^- π^0 final state in antiproton annihilation at rest in gaseous hydrogen at NTP with the OBELIX spectrometer

A spin-parity analysis of a sample of p ̅p→ K^+ K^- π^+ π^- π^0 annihilation events taken at rest in gaseous H₂ at NTP is reported. The invariant mass spectrum of the K^+ K^- π^0 system shows the presence of the E/iota resonance pattern at 1.42 GeV. The analysis of this signal confirms the results obtained by the OBELIX Collaboration in previous works, namely: the existence of two pseudoscalar states at 1.413±0.002 and 1.460 ± 0.012 GeV with widths 0.051 ±0.004 and 0.120 ± 0.015 GeV, respectively. The p ̅p system in the ³P₁ wave shows also a signal corresponding to the axial vector f₁(1420) decaying to K*{K} with mass 1.420 ± 0.003 GeV and width 0.061±0.005 GeV. A study of the incoherent phase space background shows that its origin is mostly due to the reflection of a resonant state in the K^+ K^- π^+ π^- system. The isobar decomposition of this resonant state is mainly f₀(1370)(ππ)S, its parameters are: JPC = 0⁺⁺, m = 1.670 ± 0.02 GeV and width 0.267±0.036 GeV. This signal can be probably identified with another decay mode of the f₀(1710).