Document Type


Publication Date




Publication Title

Physical Review D






032004 (1-33)


Semi-inclusive π+ electroproduction on protons has been measured with the CLAS detector at Jefferson Lab. The measurement was performed on a liquid-hydrogen target using a 5.75 GeV electron beam. The complete five-fold differential cross sections were measured over a wide kinematic range including the complete range of azimuthal angles between hadronic and leptonic planes, ϕ , enabling us to separate the ϕ-dependent terms. Our measurements of the ϕ -independent term of the cross section at low Bjorken x were found to be in fairly good agreement with pQCD calculations. Indeed, the conventional current fragmentation calculation can account for almost all of the observed cross section, even at small π+ momentum. The measured center-of-momentum spectra are in qualitative agreement with high-energy data, which suggests a surprising numerical similarity between the spectator diquark fragmentation in the present reaction and the antiquark fragmentation measured in e+e collisions. We have observed that the two ϕ -dependent terms of the cross section are small. Within our precision the cos2ϕ term is compatible with zero, except for the low-z region, and the measured cos ϕ term is much smaller in magnitude than the sum of the Cahn and Berger effects.


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© 2009 American Physical Society

Original Publication Citation

Collaboration, C., Osipenko, M., Ripani, M., Ricco, G., Avakian, H., De Vita, R., . . . Zhao, Z. W. (2009). Measurement of semi-inclusive π+ electroproduction off the proton. Physical Review D, 80(3), 032004. doi:10.1103/PhysRevD.80.032004


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