Physical Review Letters
022002 (7 pages)
Double-spin asymmetries and absolute cross sections were measured at large Bjorken x (0.25 ≤ x ≤ 0.90), in both the deep-inelastic and resonance regions, by scattering longitudinally polarized electrons at beam energies of 4.7 and 5.9 GeV from a transversely and longitudinally polarized 3He target. In this dedicated experiment, the spin structure function g(2)(3He) was determined with precision at large x, and the neutron twist-3 matrix element d(2)(n) was measured at < Q2> of 3.21 and 4.32 GeV2/c2, with an absolute precision of about 10-5. Our results are found to be in agreement with lattice QCD calculations and resolve the disagreement found with previous data at < Q2> = 5 GeV2/c2. Combining d(2)(n) and a newly extracted twist-4 matrix element f(2)(n), the average neutron color electric and magnetic forces were extracted and found to be of opposite sign and about 30 MeV/fm in magnitude.
Original Publication Citation
Posik, M., Flay, D., Parno, D. S., Allada, K., Armstrong, W., Averett, T., . . . Jefferson Lab Hall, A. C. (2014). Precision measurement of the neutron twist-3 matrix element d(2)(n): Probing color forces. Physical Review Letters, 113(2), 022002. doi:10.1103/PhysRevLett.113.022002
0000-0002-4236-0974 (Golge), 0000-0001-7282-8120 (Hyde)
Posik, M.; Flay, D.; Parrno, D. S.; Allada, K.; Armstrong, W.; Benmokhtar, F.; Canan, M.; El Fassi, L.; Golge, S.; and Hyde, C., "Precision Measurement of the Neutron Twist-3 Matrix Element d(2)(n): Probing Color Forces" (2014). Physics Faculty Publications. 205.