My research is in theoretical particle physics and quantum field theory. Field theory combines quantum theory and relativity and provides the framework for the fundamental theories of particle physics.


I have a longstanding interest in optimizing renormalized perturbation theory in Quantum Chromodynamics (QCD) and other theories. Conventional perturbation theory yields ambiguous results dependent on the arbitrary renormalization scheme choice. The "Principle of Minimal Sensitivity" approach developed in my 1981 paper resolves this issue and has some deep implications. When higher-order calculations became available in the early '90's Mattingly and I showed that optimized perturbation theory, without any extra ad-hoc inputs, predicts "freezing" behaviour at low energies, in accord with many phenomenological indications. I have recently been exploring the mathematical properties of the optimization equations in high orders with the aim of substantiating my conjecture that optimization provides an "induced convergence" mechanism, even though perturbation series in any fixed renormalization scheme are factorially divergent.