Observation of narrow (3π)± peaks in the δ and A1 regions in pp annihilations at 5.7 GeV/c

Abstract In the π + π − π ± systems of the reactions p p → K K mπ ( m =4,5) two narrow peaks are observed at the positions of the δ and A 1 mesons. The measured masses and widths are: M = (956±7) MeV , Γ =(46±22) MeV for the δ and M =(1076±5)MeV, Γ =(36 −15 +20 )MeV, for the A 1 . Their decay modes and spin-parities are shown to be mainly 3 π , J P =0 − and ϱπ , J P =1 + (D-wave) respectively.