<p>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.</p><p>In BESII, <i>e</i><sup>+</sup><i>e</i><sup>–</sup> form a charmonium initial state, which is utilised as a source for secondary particles. The analysed channels, <i>ψ</i>´→ <i>γK</i><sup>+</sup><i>K</i><sup>–</sup> and <i>ψ</i>´→ <i>γπ</i><sup>+</sup><i>π</i><sup>–</sup>, give access to intermediate scalar states such as the two glueball candidates: f<sub>0</sub>(1500) and f<sub>0</sub>(1710). The f<sub>0</sub>(1710) is indeed observed in decay into both <i>π</i><sup>+</sup><i>π</i><sup>–</sup> and <i>K</i><sup>+</sup><i>K</i><sup>–</sup> and the f<sub>0</sub>(1500) is accepted as a necessary part of the <i>π</i><sup>+</sup><i>π</i><sup>–</sup> signal at the moderate 5% level. In addition, we observe the two tensor states f<sub>2</sub>(1270) (in both channels) and f<sub>2</sub>´(1525) (in <i>K</i><sup>+</sup><i>K</i><sup>–</sup>), but the need for the f<sub>2</sub>´(1525) is not firmly established. The region around 2 GeV/<i>c</i><sup>2</sup> is fitted with an f<sub>4</sub>(2050) and an f<sub>0</sub>(2200) in <i>π</i><sup>+</sup><i>π</i><sup>–</sup>. This region is fairly flat in <i>K</i><sup>+</sup><i>K</i><sup>–</sup> with a slight peak at the f<sub>0</sub>(2200). Branching ratios for all eight channels are given. A fit to the angular distribution of ψ´→ γ f<sub>2</sub>(1270) → <i>γ π</i><sup>+</sup><i>π</i><sup>–</sup>gave two possible solutions for the relative importance of helicity projections zero, one and two.</p><p>The future <i>pp</i>bar 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 <i>J</i><i>PC</i>=1<sup>–+</sup> charmonium hybrid (<i>H</i><i>c</i>) is presented: <i>ppbar</i> → <i>H</i><i>c</i><i>π</i><sup>0</sup>/<i>η</i>, <i>H</i><i>c</i> → <i>χ</i><i>c</i><sub>1</sub> (<i>π</i><sup>0</sup><i>π</i><sup>0</sup>)<i>S–wave</i>, <i>χ</i><i>c</i><sub>1</sub> → <i>J</i>/<i>ψπ</i><sup>0</sup>, 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. </p><p>A second simulation study of <i>pp</i>bar → <i>η</i><i>c</i> → <i>γγ</i> 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%. </p><p>By assuming a constant matrix element we obtain a relation between the decay width for <i>ψ</i> → <i>pp</i>bar+<i>m</i>, which has been measured at BES for several cases, and the cross section for <i>pp</i>bar charmonium production in association with the same light meson, <i>m</i> (at for example PANDA). Cross sections of ~300–3000 pb were predicted for J/ψ production and ~30 pb for <i>ψ</i>' production. Isoscalars seem to be preferred to isovectors in <i>J</i>/<i>ψ</i> production, this might however be an artefact of simplifications within the model. A comparison with the only measured cross section, <i>pp</i>bar → <i>J</i>/<i>ψπ</i><sup>0</sup>, suggests that the model is useful as a first estimate.</p>
| Identifer | oai:union.ndltd.org:UPSALLA/oai:DiVA.org:uu-7460 |
| Date | January 2007 |
| Creators | Lundborg, Agnes |
| Publisher | Uppsala University, Nuclear Physics, Uppsala : Acta Universitatis Upsaliensis |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Doctoral thesis, comprehensive summary, text |
| Relation | Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1651-6214 ; 269 |
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