Particle Theory

Y. S. Kim's Interest in Elementary Particle Theory

I worry about the following problems in particle physics

Extended Particles: Hadrons in the quark model are quite different from hadrons in Feynman's parton picture. The question then is whether they are two distinct manifestations of the same covariant entity: one at the rest frame and the other at the infinite-momentum frame.
Fundamental Question: Hadrons are quantum bound states of quarks if the are on the table. However, for a bicycle moving with a speed close to that of light, they are collection of light-like partons whose properties are quite different from those of the quarks. Can we then settle the quarrel between these two observers?
Gauge Transformations: A particle at rest has three rotational degrees of freedom. A massless particle has one helicity degree of freedom and gauge degrees of freedom. The question then is whether they are two different manifestations of one covariant entity, as Einstein's energy-momentum relation gives two different relations for massive and massless particles.
Neutrino Polarization: Neutrino's are polarized while photons are not. I worry about whether the neutrino polarization is due to gauge invariance.

Lorentz Group: The above three problems are based on symmetry of the Lorentz group. I made a very heavy investment in this subject, and wrote many papers on applications of the Lorentz group to various problems in physics including those in particle theory and quantum optics.

Reprints: I published many papers on the above topics, primarily with D. Han, M. E. Noz, D. Son and others. Reprints are available. Send your request to yskim@umd.edu. Specify your need and explain the problem you are working on.