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Register a new userStudy of pbar-p -> eta-eta-pizero-pizero in flight
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An analysis of data on pbar-p -> eta-eta-pizero-pizero is presented at pbar beam momenta 600 to 1940 MeV/c. There is evidence for an I = 1, J^PC = 2^-+ resonance in eta-eta-pizero with mass M = 1880 +- 20 MeV and width 255 +- 45 MeV, decaying strongly a2(1320)-eta; it is too strong to be explained as the high mass tail of pi_2(1670) -> a2(1320)-eta. There is tentative evidence also for weak decays to f_0(1500)pi. It makes a natural partner to the eta 2(1860).
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A partial wave analysis of pbar-p -> eta-eta-pizero data from the Crystal Barrel experiment is made in terms of s-channel resonances. The decay channels a_0(980)-eta, f_0(1770)-pi and f_0(2105)-pi provide evidence for two I = 1 J^{PC} = 0^{-+} resonances. The first has mass M =2360 +- 25 MeV and width Gamma = 300^{+100}_{-50} MeV, and the second M =2070 pm 35 MeV, Gamma = 310^{+100}_{-50} MeV. There is also evidence for a J^{PC} = 2^{-+} state with M = 2005 +- 15 MeV and Gamma = 200 +- 40 MeV, decaying strongly to a_0(980)-pi.
We present data on pbar-p -> eta-eta-pizero at beam momenta of 600, 900, 1050, and 1200 MeV/c. At the higher three momenta, a signal is clearly visible due to pbar-p -> f_0(1770)-pizero, f_0(1770) -> eta-eta. It has mass 1770+-12 MeV and width 220+-40 MeV, where errors cover systematic uncertainties as well as statistics.
Data on pbar-p -> 3eta for beam momenta 600--1940 MeV/c are presented. The strongest channel is f_0(1500)-eta from the initial pbar-p state 1S0. Together with eta-pizero-pizero data, the 3eta data determine the branching ratio BR[f_0(1500) -> eta-eta]/BR[f_0(1500) -> pizero-pizero] = 0.42+-0.09. They are consistent with a dominant contribution from an I=0, C=+1 J^{PC} = 0^{-+} resonance observed earlier in the eta-pizero-pizero data; from the combined eta-pizero-pizero and 3eta data, its mass is M = 2320 pm 15 MeV and its width Gamma = 230+-35 MeV.
Data are presented on the reaction J/psi--> p pbar eta using 7.8 million J/psi triggers collected by the BEjing Spectrometer (BES). A partial wave analysis is performed. A clear enhancement near the p eta(pbar eta) threshold is observed. It is fitted with a JP=1/2- resonance with mass $M= 1530pm 10$ MeV and width $Gamma = 95pm 25$ MeV. In addition, there is a peak around 1650 MeV with JP=1/2- preferred also, fitted with $M =1647pm 20$ MeV and $Gamma = 145^{+80}_{-45}$ MeV. These two N* resonances are believed to be the two well established states, S11(1535) and S11(1650), respectively. It is the first partial wave study of the production of these resonances from J/psi decays.
A measurement of the pp --> p p eta reaction at the excess energy of Q = 15.5 +- 0.4 MeV has been carried out at the internal beam facility COSY-11 with an integrated luminosity of 811 nb^-1 The number of ~24000 identified events permits a precise determination of total (2.32 +- 0.05 +- 0.35 mu b) and differential cross sections. Preliminary investigations show that the angular distribution of the eta meson in the center-of-mass system is isotropic. A qualitative analysis of the Dalitz-plot distribution is presented.
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