Measurement of target and double-spin asymmetries for the (e)over-right-arrow (p)over-right-arrow -> e pi(+)(n) reaction in the nucleon resonance region at low Q(2)
PHYSICAL REVIEW C
We report measurements of target- and double-spin asymmetries for the exclusive channel (e) over right arrow (p) over right arrow - > ep(+)(n) in the nucleon resonance region at Jefferson Lab using the CEBAF Large Acceptance Spectrometer (CLAS). These asymmetries were extracted from data obtained using a longitudinally polarized NH3 target and a longitudinally polarized electron beam with energies 1.1, 1.3, 2.0, 2.3, and 3.0 GeV. The new results are consistent with previous CLAS publications but are extended to a low Q(2) range from 0.0065 to 0.35 (GeV/c)(2). The Q(2) access was made possible by a custom-built Cherenkov detector that allowed the detection of electrons for scattering angles as low as 6 degrees. These results are compared with the unitary isobar models JANR and MAID, the partial-wave analysis prediction from SAID, and the dynamic model DMT. In many kinematic regions our results, in particular results on the target asymmetry, help to constrain the polarization-dependent components of these models.
Zheng, X.; Adhikari, K. P.; Bosted, P.; Deur, A.; Drozdov, V.; El Fassi, L.; Kang, Hyekoo; Kovacs, K.; Kuhn, S.; Long, E.; Phillips, S. K.; Ripani, M.; Slifer, K.; Smith, L. C.; Adikaram, D.; Akbar, Z.; Amaryan, M. J.; Pereira, S. Anefalos; Asryan, G.; Avakian, H.; Badui, R. A.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; and Griffioen, Keith A., Measurement of target and double-spin asymmetries for the (e)over-right-arrow (p)over-right-arrow -> e pi(+)(n) reaction in the nucleon resonance region at low Q(2) (2016). PHYSICAL REVIEW C, 94(4).