<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>⁺<i>e</i>^– form a charmonium initial state, which is utilised as a source for secondary particles. The analysed channels, <i>ψ</i>´→ <i>γK</i>⁺<i>K</i>^– and <i>ψ</i>´→ <i>γπ</i>⁺<i>π</i>^–, 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 <i>π</i>⁺<i>π</i>^– and <i>K</i>⁺<i>K</i>^– and the f₀(1500) is accepted as a necessary part of the <i>π</i>⁺<i>π</i>^– signal at the moderate 5% level. In addition, we observe the two tensor states f₂(1270) (in both channels) and f₂´(1525) (in <i>K</i>⁺<i>K</i>^–), but the need for the f₂´(1525) is not firmly established. The region around 2 GeV/<i>c</i>² is fitted with an f₄(2050) and an f₀(2200) in <i>π</i>⁺<i>π</i>^–. This region is fairly flat in <i>K</i>⁺<i>K</i>^– 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) → <i>γ π</i>⁺<i>π</i>^–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^–+ charmonium hybrid (<i>H</i><i>c</i>) is presented: <i>ppbar</i> → <i>H</i><i>c</i><i>π</i>⁰/<i>η</i>, <i>H</i><i>c</i> → <i>χ</i><i>c</i>₁ (<i>π</i>⁰<i>π</i>⁰)<i>S–wave</i>, <i>χ</i><i>c</i>₁ → <i>J</i>/<i>ψπ</i>⁰, 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>⁰, suggests that the model is useful as a first estimate.</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. 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.