This thesis treats the mass range of charmonium states and excited gluonic fields in two experiments, BESII and PANDA, and outlines a phenomenological model that connects them. In BESII, e+e– form a charmonium initial state, which is utilised as a source for secondary particles. The analysed channels, ψ´→ γK+K– and ψ´→ γπ+π–, give access to intermediate scalar states such as the two glueball candidates: f0(1500) and f0(1710). The f0(1710) is indeed observed in decay into both π+π– and K+K– and the f0(1500) is accepted as a necessary part of the π+π– signal at the moderate 5% level. In addition, we observe the two tensor states f2(1270) (in both channels) and f2´(1525) (in K+K–), but the need for the f2´(1525) is not firmly established. The region around 2 GeV/c2 is fitted with an f4(2050) and an f0(2200) in π+π–. This region is fairly flat in K+K– with a slight peak at the f0(2200). Branching ratios for all eight channels are given. A fit to the angular distribution of ψ´→ γ f2(1270) → γ π+π–gave two possible solutions for the relative importance of helicity projections zero, one and two. The future ppbar experiment PANDA is still in the development phase; important physics goals have been defined and we are now taking on the laborious task of constructing a detector that is able to fulfil them. A simulation investigation of a theoretically preferred JPC=1–+ charmonium hybrid (Hc) is presented: ppbar → Hcπ0/η, Hc → χc1 (π0π0)S–wave, χc1 → J/ψπ0, with a final state of seven photons and a lepton pair. To detect this channel next to full coverage of CM phase space is needed and as little material as possible before the electromagnetic calorimeter. A second simulation study of ppbar → ηc → γγ at PANDA, suggests that the channel should be possible to detect with a signal-to-background ratio of 5±1 and a detection efficiency of at least 10%. By assuming a constant matrix element we obtain a relation between the decay width for ψ → ppbar+m, which has been measured at BES for several cases, and the cross section for ppbar charmonium production in association with the same light meson, m (at for example PANDA). Cross sections of ~300–3000 pb were predicted for J/ψ production and ~30 pb for ψ' production. Isoscalars seem to be preferred to isovectors in J/ψ production, this might however be an artefact of simplifications within the model. A comparison with the only measured cross section, ppbar → J/ψπ0, suggests that the model is useful as a first estimate.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:uu-7460 |
| Date | January 2007 |
| Creators | Lundborg, Agnes |
| Publisher | Uppsala universitet, Avdelningen för kärnfysik, Uppsala : Acta Universitatis Upsaliensis |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Doctoral thesis, comprehensive summary, info:eu-repo/semantics/doctoralThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1651-6214 ; 269 |
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