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Doctor of Philosophy (PhD)




Colin Morningstar


A new method of estimating quark propagation, known as Stochastic LapH, has
provided a way of computing many observables in lattice QCD which have previously
been inaccessible due to computational expense. In this work, the first large-scale
applications of the Stochastic LapH method to excited meson spectroscopy are presented.
We discuss the construction of single-meson and two-meson operators with
LapH smearing, and procedures for selecting and correlating large sets of these operators
are described. We then present the analysis of a 56 × 56 correlator matrix
of operators in the isovector nonstrange T+1u channel. We extract the energy of the
ρ meson, and discuss the identification and energy extractions of excited ρ mesons.
Operators are included for all
avor combinations that can result in the I = 1, S = 0
total quantum numbers of the desired symmetry channel. The correlation matrix is
calculated on 551 configurations of an anisotropic 243×128 gauge field ensemble with
clover-improved Wilson fermions. Good signal quality is obtained even for correlators
involving same-time quark lines and isoscalar mesons as part of two-meson operators.
Results are compared with experimental values compiled by the Particle Data Group.

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