Measurements of polarized photo-pion production on longitudinally polarized HD and Implications for Convergence of the GDH Integral

Abstract

We report new measurements of inclusive pion production from frozen-spin HD for polarized photon beams covering the Delta(1232) resonance. These provide data simultaneously on both H and D with nearly complete angular distributions of the spin-difference cross sections entering the Gerasimov-Drell-Hearn (GDH) sum rule. Recent results from Mainz and Bonn exceed the GDH prediction for the proton by 22 microbarns, suggesting as yet unmeasured high-energy components. Our pi0 data reveal a different angular dependence than assumed in Mainz analyses and integrate to a value that is 18 microbarns lower, suggesting a more rapid convergence. Our results for deuterium are somewhat lower than published data, considerably more precise and generally lower than available calculations.

arXiv comment4 pages, 4 figures. Submitted for publication in Physical Review Letters

References in corpus (5)

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• Analysis of Pion Photoproduction Data
• Leading and higher twists in the proton polarized structure function at large Bjorken x
• Incoherent pion photoproduction on the deuteron with polarization observables II: Influence of final state rescattering
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Cited by in corpus (15)

• The Spin Structure of the Nucleon
• Determining pseudoscalar meson photo-production amplitudes from complete experiments
• Measurement of the Q^2 Dependence of the Deuteron Spin Structure Function g_1 and its Moments at Low Q^2 with CLAS
• Measurement of the 3He Spin-Structure Functions and of Neutron (3He) Spin-Dependent Sum Rules at 0.035<Q^2<0.24 GeV^2
• The incompleteness of complete pseudoscalar-meson photoproduction
• Distillation of hydrogen isotopes for polarized HD target
• Helicity-dependent reaction \vec γ\vec d\to πNN and its contribution to the GDH sum rule for the deuteron
• A cryostat to hold frozen-spin polarized HD targets in CLAS: HDice-II
• Development of portable NMR polarimeter system for polarized HD target
• HD gas analysis with Gas Chromatography and Quadrupole Mass Spectrometer
• Measurement of nuclear spin relaxation time in lanthanum aluminate for development of polarized lanthanum target
• Measurement of the high-energy contribution to the Gerasimov-Drell-Hearn sum rule
• Measurement of the nucleon spin structure functions for 0.01<$Q^2$<1 GeV${}^2$ using CLAS
• The Gerasimov-Drell-Hearn sum-rule with nuclear targets
• Monitoring the build-up of hydrogen polarization for polarized Hydrogen-Deuteride (HD) targets with NMR at 17 Tesla