The Need for Polarization for Extracting Baryon Resonances and the NSTAR Program at CLAS

Abstract

We report on the NSTAR program in Hall B of JLab on using polarization observables to extract parameters of baryon resonances. The scientific purpose of the program is to improve the understanding of the underlying quark degrees of freedom, especially in the higher resonance regions, where we expect to uncover many of missing baryon resonances that mainly decay through multi-meson channels. With the high-quality beam of circularly-and linearly-polarized photons onto unpolarized and polarized proton and deteurium targets, and coupled with the nearly complete solid angle coverage of CLAS, we will extract the differential cross sections and associated polarization observables obtained by the photoproduction of vector mesons and kaons at center of mass energies of 1.7 to 2.2 GeV. The paper will primarily present the photon beam aspects of the excited baryon program.