This thesis is concerned with the study and improvement of methods for generating Monte-Carlo configurations used for providing non-perturbative numerical results from lattice gauge theories such as QCD, the theory of strong interactions between quarks and gluons. At present, lattice calculations require large amounts of CPU time on the largest supercomputers. In spite of this numerical assault, the majority of results generated still contain systematic errors from the use of the quenched approximation. In this approximation, employed to dramatically reduce computational costs, the effects of quantum fluctuations in the vacuum of fermion fields are ignored. Chapter 2 investigates the efficiency of a new approximate technique for dynamical fermion simulations which replaces the fermion action with the action of a large number of flavours of locally interacting auxiliary boson fields. The technique is shown to have problematic behaviour in the approach to the limit in which it exactly reproduces the required lattice gauge theory. The autocorrelation time, a measure of efficiency is shown to rise linearly in the number of boson fields employed. Chapter 3 proposes an improvement to this developing method which removes the bias of the approximation introduced. This avoids the computationally difficult approach to the exact limit of the approximation. Chapter 4 involves the calculation of the mass of the scalar glueball of QCD using large lattice spacings to avoid the high penalty for the approach to the continuum limit with an "improved" lattice action to remove the significant discretisation artifacts present at these spacings.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:660479 |
| Date | January 1995 |
| Creators | Peardon, Michael James |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/15616 |
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