A partial wave analysis of the centrally produced eta pi0 and eta pi- channels has been performed in pp collisions using an incident beam momentum of 450 GeV/c. Clear a0(980) and a2(1320) signals have been observed in S and D+ waves respectively. The dPT, phi and |t| distributions of these resonances are presented.
The reaction pp -> pf (eta eta) ps has been studied at 450 GeV/c. For the first time a partial wave analysis of the centrally produced eta eta system has been performed. Signals for the f0(1500), f0(1710) and f2(2150) are observed and the decay branching fractions of these states are determined.
The reaction pp -> pf (pi0pi0pi0) ps has been studied at 450 GeV/c. The pi0pi0pi0 effective mass spectrum shows clear eta(547) and pi2(1670) signals. Branching ratios for the eta(547) and pi_2(1670) are given as well as upper limits for the decays of the omega(782), a1(1260) and a2(1320) into 3pi0.
The reactions pp -> pf (X0) ps, where X0 is observed decaying to eta etaprime and etaprime etaprime, have been studied at 450 GeV/c. This is the first time that these channels have been observed in central production and only the second time that the etaprime etaprime channel has been observed in any production mechanism. In the eta etaprime channel there is evidence for the f0(1500) and a peak at 1.95 GeV. The etaprime etaprime channel shows a peak at threshold which is compatible with having JPC = 2++ and spin projection JZ = 0.
The reaction pp -> pf (omega omega) ps has been studied at 450 GeV/c and a spin analysis of the omega omega channel has been performed for the first time in central production. Evidence is found for the f2(1910) in the JPC = 2++ wave with spin projection JZ = 2. This is the only state observed in central production with spin projection JZ = 2. Its dPT and phi dependencies are similar to those observed for other glueball candidates. In addition, evidence is found for a state with JPC = 4++ consistent with the f4(2300). The f0(2000), previously observed in the rho rho final state, is confirmed.
A search for centrally produced charmonium states has been presented. There is no significant evidence for any charmonium production. An upper limit of 2 nb is found for the cross section of chic production using the decay chic(1P)-> J/psi gamma.
The WA102 Collaboration
,D. Barberis
,et al
.
(2000)
.
"A study of the centrally produced eta pi0 and eta pi- systems in pp interactions at 450 GeV/c"
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Andrew Kirk
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