Measurements of polarized photo-pion production on longitudinally polarized HD and Implications for Convergence of the GDH Integral
| Autor: | LEGS Spin Collaboration, Hoblit, S., Sandorfi, A. M., Ardashev, K., Bade, C., Bartalini, O., Blecher, M., Caracappa, A., D'Angelo, A., d'Angelo, A., Di Salvo, R., 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. |
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| Rok vydání: | 2008 |
| Předmět: | |
| Zdroj: | Phys.Rev.Lett.102:172002,2009 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevLett.102.172002 |
| Popis: | 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. Comment: 4 pages, 4 figures. Submitted for publication in Physical Review Letters |
| Databáze: | arXiv |
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