Measurement of ep -> ep pi(0) beam spin asymmetries above the resonance region

CLAS Collaboration, R. De Masi, M. Garcon, B. Zhao, M. J. Amaryan, P. Ambrozewicz, M. Anghinolfi, G. Asryan, H. Avakian, H. Bagdasaryan, N. Baillie, J. Ball, J. P. Ball, N. A. Baltzell, V. Batourine, M. Battaglieri, I. Bedlinskiy, M. Bellis, N. Benmouna, B. L. BermanP. Bertin, A. S. Biselli, L. Blaszczyk, S. Bouchigny, S. Boiarinov, R. Bradford, D. Branford, W. J. Briscoe, W. K. Brooks, S. Bultmann, V. D. Burkert, C. Butuceanu, J. R. Calarco, S. L. Careccia, D. S. Carman, L. Casey, S. Chen, L. Cheng, P. L. Cole, P. Collins, P. Coltharp, D. Crabb, V. Crede, N. Dashyan, E. De Sanctis, R. De Vita, P. V. Degtyarenko, A. Deur, K. V. Dharmawardane, R. Dickson, D. P. Watts

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

The beam spin asymmetry (BSA) in the exclusive reaction ep -> ep pi(0) was measured with the CEBAF 5.77 GeV polarized electron beam and Large Acceptance Spectrometer (CLAS). The x(B),Q(2),t, and phi dependences of the pi(0) BSA are presented in the deep inelastic regime. The asymmetries are fitted with a sin phi function and their amplitudes are extracted. Overall, they are of the order of 0.04-0.11 and roughly independent of t. This is the signature of a nonzero longitudinal-transverse interference. The implications concerning the applicability of a formalism based on generalized parton distributions, as well as the extension of a Regge formalism at high photon virtualities, are discussed.

Original languageEnglish
Article number042201
Pages (from-to)-
Number of pages5
JournalPhysical Review C
Issue number4
Publication statusPublished - Apr 2008


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