2011/09/30 by W. Luo, E. J. Brash, R. Gilman +126
Physics and Astronomy · #Hadron #Helicity #High-Energy Particle Collisions Research #Nuclear physics #Particle physics #Particle physics theoretical and experimental studies #Perturbative QCD #Physical chemistry #Physics #Pion #Polarization (electrochemistry) #Quantum Chromodynamics and Particle Interactions #Quantum chromodynamics #Quantum mechanics #Scattering #nucl-ex
paper · pdf · doi:10.1103/physrevlett.108.222004
6 pages and 2 figures
arxiv created 2012/03/06 · openalex publication_date 2012/05/31 · arxiv updated 2012/06/05 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present new data for the polarization observables of the final state proton in the 1H(\stackrel\ensuremath→\ensuremathγ,\stackrel\ensuremath→p)\ensuremathπ0 reaction. These data can be used to test predictions based on hadron helicity conservation and perturbative QCD. These data have both small statistical and systematic uncertainties and were obtained with beam energies between 1.8 and 5.6 GeV and for \ensuremathπ0 scattering angles larger than 75\ifmmode^∘\else\textdegree\fi in the center-of-mass frame. The data extend the polarization measurements database for neutral pion photoproduction up to E_\ensuremathγ=5.6 GeV. The results show a nonzero induced polarization above the resonance region. The polarization transfer components vary rapidly with the photon energy and \ensuremathπ0 scattering angle in the center-of-mass frame. This indicates that hadron helicity conservation does not hold and that the perturbative QCD limit is still not reached in the energy regime of this experiment.