Precision Measurement of the Neutron Twist-3 Matrix Element d[n over 2]: Probing Color Forces
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PhysRevLett.113.022002.pdf
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Author(s)
Posik, M.
Flay, D.
Parno, D. S.
Allada, Kalyan C.
Armstrong, W.
Averett, T.
Benmokhtar, F.
Camsonne, A.
Canan, M.
Cates, G. D.
Date Issued
July 2014
Journal
Physical Review Letters
Publisher
American Physical Society
Citation
Posik, M., D. Flay, D. S. Parno, K. Allada, W. Armstrong, T. Averett, F. Benmokhtar, et al. “Precision Measurement of the Neutron Twist-3 Matrix Element d[n over 2]: Probing Color Forces.” Physical Review Letters 113, no. 2 (July 2014). © 2014 American Physical Society
Version
Final published version
Abstract
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 [superscript 3]He target. In this dedicated experiment, the spin structure function [3 over g2][superscript He] was determined with precision at large x, and the neutron twist-3 matrix element d[n over 2] was measured at ⟨Q[superscript 2]⟩ of 3.21 and 4.32 GeV[superscript 2]/c[superscript 2], with an absolute precision of about 10[superscript -5]. Our results are found to be in agreement with lattice QCD calculations and resolve the disagreement found with previous data at ⟨Q[superscript 2]⟩ = 5 GeV[superscript 2]/c[superscript 2]. Combining d[n over 2] and a newly extracted twist-4 matrix element f[n over 2], the average neutron color electric and magnetic forces were extracted and found to be of opposite sign and about 30 MeV/fm in magnitude.
MIT Department
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Laboratory for Nuclear Science
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DOI of Published Version
https://doi.org/10.1103/PhysRevLett.113.022002
