Polarization Observables in Double-Charged-Pion Photo-Production with Circularly-Polarized Photons Off Transversely-Polarized Protons

Abstract

Double-pion photo-production represents one of the strongest contributions to the photonucleon total cross-section at high energies, and thus it plays an important role in probing the nucleon resonance spectrum. The polarization observables are useful because of the additional sensitivity they provide in unraveling the reaction dynamics, and so the goal of this study is to extract the specific polarization observables $$I^{\odot }$$ , $$P_{x}$$ , $$P_{y}$$ , $$P^{\odot }_{x}$$ , $$P^{\odot }_{y}$$ , for the $$\gamma p \rightarrow p \pi ^{+} \pi ^{-}$$ reaction. The data were taken as a part of the CLAS g9b (FROST) experiment at Jefferson Laboratory, which used a transversely-polarized target and a circularly-polarized photon beam with energies up to 3 GeV. The data will help deepen the current knowledge of resonance photocouplings and hadronic decays and possibly assist in identifying new baryon resonances via partial-wave analyses and in this way will contribute to a more comprehensive understanding of the strong interaction.