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Title: Light hadron spectroscopy and soft covariant gauges in lattice QCD
Author: Ryan, Sinead M.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1996
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In this thesis two aspects of Lattice QCD are studied, the light hadron spectrum and decay constants and a stochastic gauge-fixing procedure. Chapter 2 is an investigation of the effects of tadpole improvement on the Sheikholeslami-Wohlert clover action at β = 6.2. The mass spectra and decay constants of the two actions are compared using 60 gauge field configurations. Changing the value of the clover coefficient is found to have little effect on spectral quantities at this β value but reference is made to a similar study at β = 5.7 where greater effects are seen. The decay constants show a statistically significant c dependence. However, it is argued that without a non-perturbative value for the renormalisation constants ZA and ZV a conclusive statement cannot be made. In Chapter 3 a complete study of the quenched, light hadron spectrum and decay constants at β = 6.2 is done, using 220 tadpole improved gauge field configurations and quark propagators with local and fuzzed sources. Using data at two additional β values, 6.0 and 5.7 the effects of scaling are investigated. The pseudoscalar and vector decay constants are calculated and ratios of decay constants are compared with their experimental values. Chapter 4 describes a preliminary study of a new, covariant, one parameter gauge-fixing procedure. This scheme avoids the problem of Gribov copies by imposing a "soft" gauge fixing condition. Varying the gauge-fixing parameter allows a study of gauge dependence. Details of the lattice scheme and the algorithm to implement it are given. The behaviour of the internal energy of the system, the specific heat and the zero momentum gluon propagator is monitored. Results for the gauge dependence of the gluon propagator are presented.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available