First measurement of the double spin asymmetry in (e)over-right-arrow(p)over-right-arrow→e′π+ in the resonance region -: art. no. 082001

The double spin asymmetry in the (e) over right arrow(p) over right arrow --> e' pi(+) n reaction has been measured for the first time in the resonance region for four-momentum transfer Q(2) = 0.35-1.5 GeV2. Data were taken at Jefferson Lab with the CLAS detector using a 2.6 GeV polarized electron beam incident on a polarized solid NH3 target. Comparison with predictions of phenomenological models shows strong sensitivity to resonance contributions. Helicity-1/2 transitions are found to be dominant in the second and third resonance regions. The measured asymmetry is consistent with a faster rise with Q(2) of the helicity asymmetry A(1) for the F-15(1680) resonance than expected from the analysis of the unpolarized data.