Abstract
Exclusive electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in , , , and , in the range from 1.0 to , up to , and from 0.1 to 0.58. Structure functions , , and were extracted as functions of for each of 17 combinations of and . The data were compared directly with two handbag-based calculations including both longitudinal and transversity generalized parton distributions (GPDs). Inclusion of only longitudinal GPDs very strongly underestimates and fails to account for and , while inclusion of transversity GPDs brings the calculations into substantially better agreement with the data. There is very strong sensitivity to the relative contributions of nucleon helicity-flip and helicity nonflip processes. The results confirm that exclusive electroproduction offers direct experimental access to the transversity GPDs.
- Received 13 June 2012
DOI:https://doi.org/10.1103/PhysRevLett.109.112001
© 2012 American Physical Society