Study of the K+K−π+π−π0 final state in antiproton annihilation at rest in gaseous hydrogen at NTP with the OBELIX spectrometer

Abstract A spin-parity analysis of a sample of p p→K + K − π + π − π 0 annihilation events taken at rest in gaseous H 2 at NTP is reported. The invariant mass spectrum of the K + K − π 0 system shows the presence of the E / ι 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 3 P 1 wave shows also a signal corresponding to the axial vector f 1 (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 f 0 (1370)( ππ ) S , its parameters are: J PC =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 f 0 (1710).