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Title: Decays of heavy-light mesons : weak matrix elements from the lattice
Author: Maynard, Christopher Michael
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1999
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This thesis describes a numerical study of weak matrix elements of the vector and axial vector currents relevant to the semi-leptonic and leptonic decays of B and D mesons from Lattice QCD. The simulation was performed in Quenched QCD on a 243 x 48 lattice at β = 6.2. The fermionic degrees of freedom were calculated using a non-perturbatively O(a) improved action. For a pseudoscalar final state in a semi-leptonic decay, only the vector current contributes and can be parameterised by two form factors which are functions of the momentum transfer squared. The main results for the form factors of the decays B → π at zero momentum transfer are: f+ (0) = f0 (0) = 0.31+3-3 stat +8-8 sys The momentum dependence was found to be reasonably modelled by pole dominance models. The decay rate for B → π is calculated and compared to experiment allowing the CKM matrix element Vub to be extracted. Vub = 0.0027+2-2 stat +7-7 sys +9-9 exp The form factors for DK, π were calculated and the momentum dependence was found to be reasonably modelled by pole dominance. For leptonic decays of pseudoscalar mesons, the axial current is parameterised by the decay constant, for B and D decays the results are fB = 191+4-4 stat +22-22 sys MeV fD = 203+3-2 stat +22-10 sys MeV The soft pion relation for the B meson which relates the ratio fB / fπ to fo(q2max), is evaluated and found to be substantially violated.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available