The observation of. chi. sub b states in the decays of the. Upsilon. (2S)
We have conducted a search for the {chi}{sub b} and the {chi}{prime}{sub b} states in the radiative decays of the {Upsilon}(2S) and the {Upsilon}(3S), using the CLEO detector at the Cornell Electron Storage Ring (CESR). The major components of the CLEO detector used in this analysis were the inner Z proportional wire chamber, and the inner cylindrical drift chamber which are used to reconstruct charged particle tracks and thus determine their momenta. These devices are located within a soleniodal magnet of radius 1 m, length 3m and a maximum operating field of 10 kilogauss. Photons were observed via their conversion into electron-positron pairs in either the beam pipe or a 0.1 radiation length lead converter located between the inner Z proportional wire chamber and the drift chamber. The electron and positron tracks were reconstructed and a constrained fit performed. Mono-energetic photon transitions from the {Upsilon}(2S) are observed above a background largely dominated by the photons from {pi}{sup 0} decay. From observed photon yields, we infer a branching ratio for {Upsilon}(2S) {yields} {gamma} + {chi}{sub b} of 14.7 {plus minus} 4.0% and a center of gravity for the {chi}{sub b} states of 121.0 MeV. A smaller data sample taken at the {Upsilon}(3S) is used to set 90% confidence level upper limits for monoenergetic photon transitions from the {Upsilon}(3S). The significance of these results within the framework of potential models is discussed.
- Research Organization:
- Rochester Univ., NY (USA)
- OSTI ID:
- 5018945
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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