Research Program in Intermediate Energy Physics

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Experiments in meson spectroscopy test critical aspects of the standardtheory of the strong nuclear force. Although they only live for a shorttime before they decay, mesons provide a unique laboratory for the studyof the strong force because they are the simplest quark configuration,just a one quark and one antiquark. The GlueX experiment is a major newinitiative being undertaken at Jefferson Lab in Newport News, Virginiausing polarized photons from the CEBAF electron accelerator to searchfor a new class of excitations known as exotic mesons. Although exoticswere predicted based upon the standard theory over 20 years ago,conclusive experimental evidence for their existence has not yet beenestablished. The P.I. is a member of the governing board of the GlueXexperiment and has specific responsibility in the design andconstruction of the polarized photon source. A preliminary step towardsthe larger goals of GlueX was the Radphi experiment was constructedstudy the decays of a known meson, the phi(1020). The phi itself is notexotic, but some evidence pointed to the possible exotic nature of twoother mesons at around the same mass, the a0(980) and the f0(980). Radiative decays of the phi to these scalars provide an important testof this hypothesis. The experiment collected its data during a 60-dayrun in summer 2000, and is in the final stages of data analysis. TheP.I. is also involved in the Qweak experiment at Jefferson Lab, whichundertakes a precise measurement of the weak charge of the proton as asearch for physics beyond the Standard Model. In this project he hasshared responsibility for the Compton-backscatter electron polarimeter.