Quantum Chromodynamics (QCD), the dynamics of quarks and gluons, is the modern theory of hadrons (strongly interacting particles), determining their structure and interactions. The non-perturbative and perturbative properties of QCD may both be expected to be important in hadronic interactions at intermediate energies. A model which appropriately includes the long range confinement and short range asymptotic freedom aspects of QCD can be compared with experiments to clarify our understanding of the transition between these two extremes of theory.
Professor Lomon is very interested in these questions and has adapted the R-matrix boundary condition method to provide a model that may include enough of the physics to be compared with data and predict new features. Its main aspects are the inclusion of coupled isobar channels interacting via meson exchange at large range, coupled to perturbative quark/gluon degrees of freedom at short range. The model has been applied to several baryon-baryon systems (of strangeness 0, -1 and 2) and to the strangeness +1 kaon-nucleon system, successfully predicting their known properties and predicting new “exotic” resonances related directly to the behavior of simple multi-quark configurations.
There is some experimental evidence for the existence of these resonances. Present research is concentrating on the observable properties of the S=-2 baryon-baryon system, which is expected to have a low energy resonance; refining predictions in the S=0 nucleon-nucleon system, for which quality data is being produced at new intermediate energy accelerators; and on the high momentum transfer electromagnetic form-factors of the deuteron to compare with new data from the energy electron accelerator at Jefferson National Laboratory.