I am currently at work on a measurement of the various electromagnetic form factors of protons and neutrons. This physics project has spurred much of the mathematical work on disconnected diagrams referred to above. One of the most interesting topics being studied experimentally in my field is the topic of so called “strange” form factors. These correspond to the contributions of the strange quark to the electromagnetic properties of mesons and baryons. These quantities have proven to be extremely elusive to calculate and the only real hope of calculating them from first principles is from the lattice. I am now in the process of writing a paper using the techniques of what is called chiral perturbation theory to try to extrapolate the lattice data to the small quark mass regime.
Another project that I have recently begun with Prof. Frank Lee of George Washington University and Prof. Joe Christensen of McMurry University is a reinvestigation of the effects of a strong electric field on the masses of various mesons and baryons. I say reinvestigation because I initially stutied this effect over a decade ago with Richard Woloshyn and Rudolf Fiebig. This effect is called polarizability and corresponds to the distortion of shape of the particle in the electromagnetic field. Our initial investigation was for an electric field; now in addition we are investigating the effects a magnetic field on these particles. We hope to compare with the experimental numbers which are now available on these quantities. I am posting a PowerPoint presentation I made in Pittsburgh at the Lattice Hadron Physics Collaboration meeting (on 11-12-04) for those who want more details:Pittsburgh Powerpoint talk
Besides the above, I am working on other topics in the lattice field as well. I am indebted to many colleagues and organizations for the progress made on these subjects and other research work. In particular, most of my computer time has come through grants from the National Center for Supercomputing Applications (NCSA) in Champaign-Urbana, Illinois. I have also had supporting monetary grants from the National Science Foundation (NSF) since 1992. Even people with modest computer budgets can now participate in the exciting attempt to understand nature at it’s most basic level!