JLAB/CLEO

Part of Experimental Particle Physics

The longstanding effort of studying nuclear physics in our department evolved into a group in medium energy physics during the 1980’s. The group played a leading role at Jefferson Lab, building a major piece of equipment for CEBAF Large Acceptance Spectrometer (CLAS) (http://www.jlab.org/Hall-B) in the remodeled Nuclear Physics Lab (NPL). Dytman was CLAS Collaboration Chairman during the first years of data taking and had an influential role in the development of the collaboration. The physics focus at that time was baryon spectroscopy and our visibility was excellent. Dytman and Mueller studied meson-baryon resonances and Dytman developed a multi-channel model to interpret a large range of data. However, physics interests evolve and the group shifted to CLEO (e+e- collider at Cornell University, http://www.lns.cornell.edu/public/CLEO/) to study mesons and more fundamental topics.

The present effort in this area is now small as faculty members have shifted their activities to more current HEP topics. Swanson has had great success in phenomenological studies of the new charmed particles recently discovered at CLEO, BaBar, Belle, and CDF. About six new narrow states have been found and existing models have been at a loss to explain them. Swanson successfully developed models based on existing ideas for some of these new particles. Although explanations derived from quark-quark and meson-meson interactions have been helpful to understand some properties, our understanding is still incomplete. Dytman and Savinov are completing interpretations of existing data. Dytman is trying to understand D hadronic decays with a multi-channel model. This will fold existing  and K scattering amplitudes into a description of all K final states in D0 or D0 decay. The main goal is to provide a model that can be used for a description of B±®K±[D0/D0], D®KSp+p- decays, the best existing method to determine the CP mixing angle g(f3). Savinov is looking for evidence of lepton symmetry violation in  decay. Specifically, he is looking for evidence of U(1S)®tedecay which could only happen through a mechanism outside the well-established standard model.