Research Interests

My research has focused on hadron physics through the study of hadron spectra and structure. The two approaches that I have used are Hamiltonian light-front field theory and lattice field theory. It is important to understand a problem with both analytic and numerical methods. The intuition gained from one can be used to guide the other and vice versa. In the end the two methods better converge.

The bulk of my dissertation is two analytic applications of Hamiltonian light-front QED. The first example shows that the correct angular momentum multiplets arise in the ground-state spin splittings of positronium (a nontrivial fact since the rotation generators are not kinematic on the light front). The second example shows that the dominant part of the Lamb shift in hydrogen arises in a systematic way. These analytic calculations lay the groundwork for precision bound-state calculations in QCD.

My postdoctoral research focused on lattice NRQCD. The two systematic errors of concern here are finite lattice spacing errors and relativistic corrections. The former error is emphasized in simulations of vector decay constants in quarkonia. Plaquettes and rectangles, tadpole improvement of the links, and perturbative one-loop matching are also included in the analysis. My LATTICE98(heavyqk) contribution has some of these simulations in it. These simulations are consistent with the decay constants of the vector mesons being proportional to the square root of their mass, which agrees with the empirical fact that the leptonic width of vector mesons is basically a constant (12 keV) times the quark charge squared. The pseudoscalar decay constant of the B(c) meson is included in the following work. Future work includes (1) adding higher order relativistic corrections to the above decay constant simulations, (2) looking at semileptonic decays of the B(c) meson, and (3) including anisotropic lattices in the analysis in order to obtain better statistics.

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