Exclusive Leptoproduction of Real Photons on a Longitudinally Polarised Hydrogen Target
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چکیده
Polarisation asymmetries are measured for the hard exclusive leptoproduction of real photons from a longitudinally polarised hydrogen target. These asymmetries arise from the deeply virtual Compton scattering and Bethe-Heitler processes. From the data are extracted two asymmetries in the azimuthal distribution of produced real photons about the direction of the exchanged virtual photon: AUL with respect to the target polarisation and ALL with respect to the product of the beam and target polarisations. Results for both asymmetries are compared to the predictions from a generalised parton distribution model. The sinφ and cos(0φ) amplitudes observed respectively for the AUL and ALL asymmetries are compatible with the sizeable predictions from the model. Unexpectedly, a sin(2φ) modulation in the AUL asymmetry with a magnitude similar to that of the sinφ modulation is observed.
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تاریخ انتشار 2010