Partial wave analysis of p̄p→π−π+, π0π0, ηη and ηη′

Abstract A partial wave analysis is presented of Crystal Barrel data on p p→π 0 π 0 , ηη and ηη′ from 600 to 1940 MeV/c, combined with earlier data on dσ/dΩ and P for p p→π − π + . The following s -channel I=0 resonances are identified: (i) J PC =5 −− with mass and width ( M , Γ ) at ( 2295±30 , 235 +65 −40 ) MeV, (ii) J PC =4 ++ at ( 2020±12 , 170±15 ) MeV and ( 2300±25 , 270±50 ) MeV, (iii) 3 D 3 J PC =3 −− at ( 1960±15 , 150±25 ) MeV and ( 2210±40 , 360±55 ) MeV, and a 3 G 3 state at ( 2300 +50 −80 ,340±150) MeV, (iv) J PC =2 ++ at ( 1910±30 , 260±40 ) MeV, ( 2020±30 , 275±35 ) MeV, ( 2230±30 , 245±45 ) MeV, and ( 2300±35 , 290±50 ) MeV, (v) J PC =1 −− at ( 2005±40 , 275±75 ) MeV, and ( 2165±40 , 160 +140 −70 ) MeV, and (vi) J PC =0 ++ at ( 2005±30 , 305±50 ) MeV, ( 2105±15 , 200±25 ) MeV, and ( 2320±30 , 175±45 ) MeV. In addition, there is a less well defined 6 ++ resonance at 2485±40 MeV, with Γ=410±90 MeV. For every J P , almost all these resonances lie on well defined linear trajectories of mass squared versus excitation number. The slope is 1.10±0.03 GeV 2 per excitation. The f 0 (2105) has strong coupling to ηη , but much weaker coupling to π 0 π 0 . Its flavour mixing angle between q q and s s is (59–71.6) ° , i.e. dominant decays to s s . Such decays and its strong production in p p interactions strongly suggest exotic character.