Measurement of beam-spin asymmetries for π+ electroproduction above the baryon resonance region

H. Avakian, V. D. Burkert, L. Elouadrhiri, N. Bianchi, G. Adams, A. Afanasev, P. Ambrozewicz, E. Anciant, M. Anghinolfi, D. S. Armstrong, B. Asavapibhop, G. Audit, T. Auger, H. Bagdasaryan, J. P. Bail, S. Barrow, M. Battaglieri, K. Beard, M. Bektasoglu, M. BellisN. Benmouna, A. S. Biselli, S. Boiarinov, B. E. Bonner, S. Bouchigny, R. Bradford, D. Branford, W. K. Brooks, C. Butuceanu, J. R. Calarco, D. S. Carman, B. Carnahan, C. Cetina, L. Ciciani, P. L. Cole, A. Coleman, D. Cords, P. Corvisiero, D. Crabb, H. Crannell, J. P. Cummings, E. DeSanctis, R. DeVita, P. V. Degtyarenko, H. Denizli, L. Dennis, K. V. Dharmawardane, C. Djalali, G. E. Dodge, D. Doughty, P. Dragovitsch, Michael Dugger, S. Dytman, O. P. Dzyubak, M. Eckhause, H. Egiyan, K. S. Egiyan, A. Empl, P. Eugenio, R. Fatemi, R. J. Feuerbach, J. Ficenec, T. A. Forest, H. Funsten, S. J. Gaff, G. Gavalian, S. Gilad, G. P. Gilfoyle, K. L. Giovanetti, P. Girard, C. I.O. Gordon, K. Griffioen, M. Guidal, M. Guillo, L. Guo, V. Gyurjyan, C. Hadjidakis, R. S. Hakobyan, J. Hardie, D. Heddle, P. Heimberg, F. W. Hersman, K. Hicks, R. S. Hicks, M. Holtrop, J. Hu, C. E. Hyde-Wright, Y. Ilieva, M. M. Ito, D. Jenkins, K. Joo, J. H. Kelley, J. Kellie, M. Khandaker, D. H. Kim, K. Y. Kim, K. Kim, M. S. Kim, W. Kim

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157 Scopus citations

Abstract

We report the first evidence for a nonzero beam-spin azimuthal asymmetry in the electroproduction of positive pions in the deep-inelastic kinematic region. Data for the reaction ep→e′ π+X have been obtained using a polarized electron beam of 4.3 GeV with the CEBAF Large Acceptance Spectrometer at the Thomas Jefferson National Accelerator Facility. The amplitude of the sin φ modulation increases with the momentum of the pion relative to the virtual photon, z. In the range z=0.5-0.8 the average amplitude is 0.038±0.005 ±0.003 for a missing mass Mx> 1.1 GeV and 0.037±0.007±0.004 for Mx> 1.4 GeV.

Original languageEnglish (US)
Article number112004
JournalPhysical Review D
Volume69
Issue number11
DOIs
StatePublished - 2004

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

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