Phys. Rev. Lett. 91, 022003 (2003) [5 pages]Cross-Section Measurement of Charged-Pion Photoproduction from Hydrogen and DeuteriumReceived 8 November 2002; published 11 July 2003 We have measured the differential cross section for the γn→π-p and γp→π+n reactions at θc.m.=90° in the photon energy range from 1.1 to 5.5 GeV at Jefferson Lab (JLab). The data at Eγ≳3.3 GeV exhibit a global scaling behavior for both π- and π+ photoproduction, consistent with the constituent counting rule and the existing π+ photoproduction data. Possible oscillations around the scaling value are suggested by these new data. The data show enhancement in the scaled cross section at a center-of-mass energy near 2.2 GeV. The cross section ratio of exclusive π- to π+ photoproduction at high energy is consistent with the prediction based on one-hard-gluon-exchange diagrams. © 2003 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevLett.91.022003
DOI:
10.1103/PhysRevLett.91.022003
PACS:
13.60.Le, 24.85.+p, 25.10.+s, 25.20.–x
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