Search

Data are reported on p p→π 0 π 0 over the range of laboratory momenta 600 to 1940 MeV/c. The shapes of angular distributions are similar to earlier data of Dulude et al. above 1100 MeV/c, but show some systematic disagreements. The absolute normalisation disagrees seriously. An amplitude analysis favours the normalisation reported here.

Data taken with the Crystal Barrel detector on p p→ηη and ηη′ are presented from 600 to 1940 MeV/c. The f0(2105) appears strongly in the ηη channel with mass and width consistent within errors with earlier data. It is produced strongly in p p interactions, but with large branching ratio to ηη compared with ππ. This is incompatible with an unmixed non-strange q q state.

We report a partial wave analysis 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 + . Most of the q q resonances expected in this mass range and in these channels are identified. Observed masses follow a simple systematic pattern of linear trajectories of mass squared v. radial quantum number n, with a slope of 1.10±0.03 Gev2 per unit of n.

Data are presented on the reaction pbar-p -> omega-omega-pizero at rest from the Crystal Barrel detector. These data identify a strong signal due to f2(1565) -> omega-omega. The relative production from initial pbar-p states 3P2, 3P1 and 1S0 is well determined from omega-omega decay angular correlations; P-state annihilation dominates strongly. A combined fit is made with data on pbar-p -> 3pizero at rest, where f2(1565) -> pizero-pizero is observed.

Antiproton-proton annihilation into π 0 π 0 η has been studied with incident beam momenta of 0.6 to 1.94 GeV/c. The main aim is to look for resonances formed by p p and decaying into π 0 π 0 η . Resonances observed are: two 4 ++ resonances with mass and width (M, Γ ) at (2044, 208) MeV and (2320±30, 220±30) MeV; three 2 ++ resonances at (2020±50, 220±70) MeV, (2240±40, 170±50) MeV and (2370±50, 320±50) MeV; two 3 ++ resonances at (2000±40, 250±40) MeV and (2280±30, 210±30) MeV; a 1 ++ resonance at (2340±40, 340±40) MeV; and two 2 −+ resonances at (2040±40, 190±40) MeV and (2300±40, 270±40) MeV.

We present data on p p→3π 0 at nine p momenta from 600 to 1940 MeV/c. This process is dominated by the f2(1270)π0 channel, where we observe I=1 resonances with the following masses and widths: 4++(2260±15), Γ=180±20 MeV, 4++(2005±25), Γ=360±80 MeV, 3++(2310±40), Γ=180+120−60 MeV, 3++(2070±20), Γ=170±40 MeV, 2++(2280±30), Γ=280±50 MeV, 2++(2100+10−30), Γ=360+40−100 MeV, 1++(2100±20), Γ=300+30−60 MeV, and 1++(2340±40), Γ=230±70 MeV.

Data taken with the Crystal Barrel detector on p p→π 0 η and π 0 η ′ are presented at p momenta from 600 to 1940 MeV/c. A partial wave analysis finds two alternative solutions, one significantly preferred over the other. Both contain resonances of similar masses and widths, but different coupling constants and phases. The favoured solution contains a J PC =0 ++ resonance at 2025±30 MeV with Γ =330±75 MeV, and three 2 ++ resonances as follows: (i) at 1990 +15 −30 MeV with Γ =190±50 MeV (dominantly 3 P 2 ), (ii) at 2060±20 MeV with Γ =195±30 MeV (dominantly 3 F 2 ), (iii) at 2265±20 MeV with Γ =235 +60 −35 MeV (dominantly 3 F 2 ), There are two 4 ++ resonances at 2025±40 MeV with Γ =250 +80 −55 MeV and at 2300±20 MeV with Γ =230±40 MeV. Errors cover systematic errors and statistical fluctuations of 3 σ .

We report results of a high resolution search for the tensor glueball candidate ξ(2230) in a p p formation experiment. π0π0 and ηη decay channels were measured in a scan of the mass region 2220 MeV to 2240 MeV. No evidence for the existence of ξ(2230) was found. 95% confidence upper limits for the possible existence of ξ are presented.