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The annihilation channels pp!! 0 , !, ! 0 were studied with the Crystal Barrel detector at LEAR at p-momenta of 600, 1200, and 1940 MeV=c. In most cases angular distributions were measured which allowed a complete J P-analysis using the helicity formalism. The contribution of all relevant initial states could be determined. The maximal contributing angular(More)
  • Barrel CollaborationA . Abele, B . Adomeit, +69 authors Bing-Song Zou
  • 2007
Antiproton-proton annihilation into 0 has been studied with the Crystal Barrel spectrometer at CERN at an incident beam momentum of 1.94 GeV/c. The data were taken with a trigger requiring neutral nal states. A new isovector state, the a2(1660) decaying to 0 , is observed. In the invariant mass region around 2.1 GeV=c 2 , strong production of a heavy(More)
Single pi(0) photoproduction has been studied with the CB-ELSA experiment at Bonn using tagged photon energies between 0.3 and 3.0 GeV. The experimental setup covers a very large solid angle of approximately 98% of 4pi. Differential cross sections dsigma/dOmega have been measured. Complicated structures in the angular distributions indicate a variety of(More)
The photoproduction of η-mesons off different nuclei has been measured with the CBELSA/TAPS detector system for incident photon energies between 1500 2200 MeV. The transparency ratio has been deduced and compared to theoretical calculations describing the propagation of η-mesons in nuclei. The comparison indicates a width of the η-meson of the order of Γ =(More)
We report results of a high resolution search for the tensor glueball candidate ξ(2230) in a p̄p formation experiment. ππ 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. As soon as the(More)
We report the first observations of Pontecorvo reactions of the type pd → Xn. We fully reconstruct the outgoing meson and, for antiprotons stopped in liquid deuterium, we measure: BR(pd → π0n ) = (7.03 ± 0.72) x 10-6, BR(pd → ηn) = (3.19 ± 0.48) x 10-6, BR(pd → ωn ) = (22.8 ± 4.1) x 10-6, BR(pd → η'n ) ≤ 14 x 10-6 (at 95% confidence level). Assuming charge(More)
The photoproduction of omega mesons on nuclei has been investigated using the Crystal Barrel/TAPS experiment at the ELSA tagged photon facility in Bonn. The aim is to study possible in-medium modifications of the omega meson via the reaction gamma + A --> omega + X --> pi(0)gamma + X('). Results obtained for Nb are compared to a reference measurement on a(More)
The reaction γp → pπη has been studied with the CBELSA detector at the tagged photon beam of the Bonn electron stretcher facility. The reaction shows contributions from ∆(1232)η, N(1535)π and pa0(980) as intermediate states. A partial wave analysis suggests that the reaction proceeds via formation of six ∆ resonances, ∆(1600)P33, ∆(1920)P33, ∆(1700)D33 ,(More)
We present a measurement and partial wave analysis of the nal state KLK of pp annihilation at rest in liquid hydrogen. This reaction is important for the study of the KK decay mode of scalar resonances, in particular the isovectors a0(980) and a0(1450). The determination of the a0(1450) production also xes the KK coupling of the isoscalar f0(1500) which is(More)