Steve Spanier

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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)
In contrast to the vector and tensor mesons the identification of the scalar mesons is a long standing puzzle. The problem originates from their large decay widths causing a strong overlap of individual resonances within the same partial wave, and at the same time several decay channels open up within a short mass interval. In addition the KK and ηη(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)
The 0 momentum dependence of the decay ! + ? 0 has been measured with the Crystal Barrel detector. The analysis is based on 3230 events. The results of this independent measurement are compared to new chiral perturbation theory calculations and previous measurements. The calculation of the amplitude of the decay into three pions has been a longstanding(More)
I. Introduction: In contrast to the vector and tensor mesons, the identification of the scalar mesons is a long-standing puzzle. Scalar resonances are difficult to resolve because of their large decay widths which cause a strong overlap between resonances and background, and also because several decay channels open up within a short mass interval. In(More)
The distribution of m(+ ?) in the decay 0 ! + ? has been measured with the Crystal Barrel detector. The results are based on a total of 7392 observed 0 decays. The box anomaly constant is extracted from this and its value is found to agree well with theoretical expectations. The pseudoscalar nonet parameters (f 1 , f 8 and PS) are determined. Finally, we nd(More)
In last year's annual report we announced that we had joined the LHC/CMS Collaboration at the Large Hadron Collider at CERN 1]. B-physics at LHC, on which we plan to concentrate, requires a good reconstruction capability for secondary ver-tices from B-decays. We are therefore contributing to the inner tracker, in particular the silicon pixel detector, its(More)
I. Introduction: In contrast to the vector and tensor mesons, the identification of the scalar mesons is a long-standing puzzle. Scalar resonances are difficult to resolve because of their large decay widths, which cause a strong overlap between resonances and background, and also because several decay channels open up within a short mass interval. In(More)