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

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-H...

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Published in:arXiv.org 2008-08
Main Authors: LEGS Spin Collaboration, Hoblit, S, Sandorfi, A M, Ardashev, K, Bade, C, Bartalini, O, Blecher, M, Caracappa, A, D'Angelo, A, d'Angelo, A, R Di Salvo, Fantini, A, Gibson, C, Glueckler, H, Hicks, K, Honig, A, Kageya, T, Khandaker, M, Kistner, O C, Kizilgul, S, Kucuker, S, Lehmann, A, Lowry, M, Lucas, M, Mahon, J, Miceli, L, Moricciani, D, Norum, B, Pap, M, Preedom, B, Seyfarth, H, Schaerf, C, Stroeher, H, Thorn, C E, Whisnant, C S, Wang, K, Wei, X
Format: Article
Language:English
Subjects:
Convergence
Dependence
Deuterium
Photon beams
Online Access:Get full text
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Summary: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.
ISSN:2331-8422
DOI:10.48550/arxiv.0808.2183