We report measurements of target- and double-spin asymmetries for the exclusive channel ⃗e⃗p→eπ+(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 Q2 range from 0.0065 to 0.35(GeV/c)2. The Q2 access was made possible by a custom-built Cherenkov detector that allowed the detection of electrons for scattering angles as low as 6∘. 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.
Physical Review C
Zheng, X.; Biselli, Angela; and CLAS Collaboration, "Measurement of target and double-spin asymmetries for the e ⃗ p ⃗→ e π+(n) reaction in the nucleon resonance region at low Q 2" (2016). Physics Faculty Publications. 113.
Zheng X, Adhikari KP, Bosted P, Deur A, Drozdov V, El Fassi L, Kang H, Kovacs K, Kuhn S, Long E, Phillips SK., Biselli, Angela, et al [CLAS Collaboration]. "Measurement of target and double-spin asymmetries for the e ⃗ p ⃗→ e π+(n) reaction in the nucleon resonance region at low Q 2." Physical Review C 94, no. 4 (2016): 045206.