We present studies of single-spin asymmetries for neutral pion electroproduction in semi-inclusive deep-inelastic scattering of 5.776 GeV polarized electrons from an unpolarized hydrogen target, using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. A substantial sinφh amplitude has been measured in the distribution of the cross section asymmetry as a function of the azimuthal angle φh of the produced neutral pion. The dependence of this amplitude on Bjorken x and on the pion transverse momentum is extracted with significantly higher precision than previous data and is compared to model calculations.
|Original language||English (US)|
|Number of pages||6|
|Journal||Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics|
|State||Published - Oct 25 2011|
Bibliographical noteFunding Information:
We thank A. Afanasev, A. Bacchetta, L. Gamberg, A. Kotzinian, A. Prokudin, A. Metz and F. Yuan for useful and stimulating discussions. We would like to acknowledge the outstanding efforts of the staff of the Accelerator and the Physics Divisions at JLab that made this experiment possible. This work was supported in part by the National Science Foundation , the Italian Istituto Nazionale di Fisica Nucleare , the French Centre National de la Recherche Scientifique , the French Commissariat à lʼEnergie Atomique , the National Research Foundation of Korea , the UK Science and Technology Facilities Council (STFC ), the EU FP6 (HadronPhysics2, Grant Agreement No. 227431 ), the Physics Department at Moscow State University and Chile grant FONDECYT No. 1100872 . The Jefferson Science Associates (JSA) operates the Thomas Jefferson National Accelerator Facility for the United States Department of Energy under contract DE-AC05-06OR23177.
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