M.Sc. (Physics) / The differential cross-section for p(e, e¡ä¦Ø)p has been studied at Q2 ¡« 5.5 (GeV/c)2. Here Q2 represents the four momentum squared of the virtual photon in the excitation of baryonic resonances by an electron projectile. The excitation cross-section for the baryonic resonances and their de-excitation rates and channels provides information on the underlying structure of QCD. The selection of the ¦Ø decay channel constrains the particular baryonic resonances that contribute to the measured cross-section. A significant aspect of the data presented from W = 1.72 GeV to W = 1.92 GeV is that the Q2 falls in the region where the transition from non-pertubative processes characterised by constituent quarks dominate to the regime where the hard processes are expected to play an increasing important role. This is therefore an interesting region to acquire further data. In order to extract the ¦Ø-meson differential cross section from the JLAB data, the data was compared to a full Monte Carlo simulation of the detector based on events generated for omega production in a way that the production cross section was varied to achieve a match to the data. The binning selected for this procedure takes into account the measure of robustness of the stripping of the ¦Ø peak from the multi-pion background as well as the statistics in the measured data and the Monte Carlo simulation of the signal and background physics [1]. An error estimation technique for the cross section was based on determining the dependence via the Monte Carlo simulation of the extracted cross section parameters on the experimental set-up (including parameters for the spectrometer, target beam geometries and performance). We compare our results with a Regge-based model for hadronic content in the t-channel exchange of a photon in Q2 region of overlap. There is an extension of this data into a completely new region, which is the highest yet measured. The result from the study of baryonic excitation via the ¦Ø channel gives a good correlation between theory and experiment in the overlapped kinematic regime of the used theoretical simulation.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:11684 |
| Date | 15 July 2014 |
| Creators | Unwuchola, Doomnull Attah |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Johannesburg |
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