Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.795385
Title: Properties of bose-mesons
Author: Power, E. A.
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1951
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Abstract:
The Thesis contains an analysis of the properties of the pi-meson. Current meson theory is used in an attempt to distinguish between possible meson types. After a survey of the experimental data involving mesons as real particles, there is a brief summary of the theory involved. An approximate method is proposed for the computation of cross-sections for meson processes involving matrix elements over exact nucleon eigenstates. The validity of this approach, the distorted wave approximation, is considered in detail for spin zero mesons. Comparison is also made with other phenomenological approaches. The distorted wave approximation is used to calculate cross-sections for the production of pi-mesons in nucleon-nucleon collisions under certain simplifying assumptions concerning the nuclear forces. For a final continuous nuclear relative motion, it is found that low energy nucleon states are favoured. This, in the case of a final neutron-proton system, together with a large contribution from transitions to a final bound deuteron, leads to a meson spectrum well peaked at the highest allowed energies in agreement with recent experiments. The total cross-section depends more on the shape and size of the inter-nucleon potential than on the meson type, but the spectrum at a given angle, and, more particularly, the angular distribution, are critically dependent on the parity of the meson produced. A comparison with experiment favours scalar mesons. There is also a consideration of the relatively small cross-section for the production of neutral pi-mesons in the observations of simple collisions. The absorption of pi-mesons by nuclei is then discussed on the assumption that capture takes place from the close shells of the meson-nuclear system. Detailed calculations are presented for the direct capture by heavy nuclei, and for various capture processes in Deuterium. When compared with recent observations, the selection rules for the absorption of mesons in light nuclei favour pseudoscalar mesons. The final problem considered is of a different character, and consists of a field theoretical calculation using Pauli regulators with the Feynman technique. It concerns the decay of heavy neutral bosons to two pi-mesons through an assumed nucleon coupling. Comparison is made with the various V-meson decays reported in cosmic ray photographs. Chapter Six summarises the contemporary position of the relation of meson theory in the light of the calculations presented in this paper, with experiment.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.795385  DOI: Not available
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