Measurements of the polarization observables IS and Ic for p→pπ[sup +]π[sup −] using the clas spectr

Abstract

Constituent Quark Models predict an excited baryon spectrum much richer in resonances than that which has been observed experimentally, the so-called missing resonance problem. Evidence for the production of these short-lived states may come about through measurements of quantities called polarization observables. These observables occur when the constraint of polarization is imposed on the reactions and are highly sensitive to resonance production. The expected sequential decay of these N* resonances via πΔ and NΔ intermediate states makes the double pion final state an attractive final state to study to reveal these missing resonances. In recent years, both single-and double-polarization experiments have been carried out as part of the N* program at Jefferson Lab in Newport News, Virginia with the goal of resolving this missing resonance problem. One such polarized photoproduction experiment used linearly polarized photons incident on an unpolarized LH2 target. The analysis of γp→pπ+π− reactions found in these polarized photoproduction data using the power of a kinematic fitter results in highly accurate measurements of these observables. The analysis of this pπ+π− final state and the extraction of two such observables, IS and Ic, will be discussed.