High-precision lattice QCD for standard and nonstandard model physics

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This grant is directed towards the study of the quark and gluon substructure of matter. Quarks and gluons are the elementary constituents of hadrons (literally, "strongly-interacting particles") such as the proton and neutron. The complete theory of quark and gluon interactions is called Quantum Chromodynamics (QCD). We have confidence that QCD is correct because of theoretical techniques that permit accurate calculations of certain processes, such as those involving high-energy collisions between hadrons. However it is much more difficult to reliably calculate low-energy properties of hadrons, such as their masses and decay rates, because the only available technique (so-called lattice QCD) requires numerical simulations on very large computer clusters. Until recently it was not possible to do lattice QCD simulations of sufficient precision even on the largest available computer clusters. Fortunately, recent theoretical developments have dramatically reduced the amount of computer power that is required. My work over the past few years, as part of the HPQCD collaboration, a group of theorists in the U.S., Canada, and the U.K., has resulted in several high-impact tests and predictions of the theory, at a heretofore unprecedented level of precision. Much additional work is required in order to fully exploit these new theoretical developments, and this is the subject of the proposed research program. This work is important because it will have a strong bearing on the interpretation of experiments which may reveal new physical phenomena. The results of lattice QCD simulations are generally required in order to properly interpret the results of these experiments. The work to be done under this grant is centered on some key elements of the theoretical analysis that is needed in order to properly use and interpret the results of the numerical simulations, and will continue the involvement of my SFU research group with the HPQCD collaboration.