Weak Interactions in Lattice Quantum Chromodynamics.
Abstract
Available from UMI in association with The British Library. Requires signed TDF. A method of calculating matrix elements for weak interactions between strongly bound hadronic states in the context of staggered fermion lattice quantum chromodynamics is described and implemented. After reviewing the reduction of weak interactions to an effective fourpoint interaction, the construction from staggered fermion fields of the fourfermion operators mediating the weak decays, and of two fermion operators exciting initial and final meson states is outlined. A method of evaluating the correlators of meson states with the fourfermion operators is presented, that exploits the flavour structure of staggered fermions to require a minimum of computation on each background gauge field. In order to relate the lattice correlators to continuum matrix elements, a program of perturbative calculations is initiated with the calculation of the finite renormalization connecting staggered bilinear operators with their continuum counterparts. This is extended by a partial sum of a class of Feynman diagrams conducing the dominant effect of multiplicative suppression of pointsplit operators by fluctuation in the background gauge fields. The results are presented in an orthonormal basis of the lattice symmetry group, and Ward identities are used as checks on the results. The perturbative calculations are then extended to the fourfermion operators found in the effective weak Hamiltonian, with both the discrete flavour structures appropriate to the use of pseudoGoldstone Bosons for mesons, and those resulting in a minimum of computation. Finally, the numerical work is described. This includes analysis of statistical errors, the validity of the flavour symmetry assumptions, and results for the isospin dependence of Ktopi amplitudes.
 Publication:

Ph.D. Thesis
 Pub Date:
 1988
 Bibcode:
 1988PhDT.......236S
 Keywords:

 Physics: Elementary Particles and High Energy