Deep inelastic scattering of polarized electrons by polarizedHe3and the study of the neutron spin structure

Abstract

The neutron longitudinal and transverse asymmetries A n 1 and A n 2 have been extracted from deep inelastic scattering of polarized electrons by a polarized 3 He target at incident energies of 19.42, 22.66 and 25.51 GeV. The measurement allows for the determination of the neutron spin structure functions g n 1 (x; Q 2 ) and g n 2 (x; Q 2 ) over the range 0:03 < x < 0:6 at an average Q 2 of 2 (GeV=c) 2 . The data are used for the evaluation of the Ellis-Ja e and Bjorken sum rules. The neutron spin structure function g n 1 (x; Q 2 ) is small and negative within the range of our measurement, yielding an integral R 0:6 0:03 g n 1 (x)dx = 0:028 0:006 (stat) 0:006 (syst). Assuming Regge behavior at low x, we extract n 1 =

Helicity-dependent generalized parton distributions in constituent quark models

“…[47,48,49,50] for the proton and from Refs. [51,52,53,54,55] for the neutron. The predicted SU (6) values are indicated by the dot-dashed line.…”

A new evaluation of polarized parton densities in the nucleon

“…In this paper we present an updated version of our NLO polarized parton densities in both the MS and the JET (or so-called chirally invariant) [2] factorization schemes as well as the LO ones determined from the world data [1,3,4] on inclusive polarized DIS. Comparing to our previous analysis [5]: i) For the axial charges a 3 and a 8 their updated values are used [6,7]: …”

The αS3 approximation of quantum chromodynamics to the Ellis-Jaffe sum rule

“…The discovery of the disagreement between the combined EMC-SLAC data [1,2] and the constituent quark model expectation [3] 1 0 dxg p 1 (x, Q 2 ) ≈ 0.15|g A | attracted a lot of attention and triggered intensive research in the field of polarized deep inelastic scattering. More recently, deuterium scattering data of the SMC [4] and of the E143 [5] collaborations, and 3 He scattering data of the E142 [6] and E154 [7] collaborations also allowed the determination of the neutron sum rule 1 0 dxg n 1 (x, Q 2 ) and the Bjorken sum rule [8] 1 0 dx[g p 1 (x, Q 2 ) − g n 1 (x, Q 2 )]. At present the Bjorken sum rule is confirmed at the 8% level [9] which is an important experimental test of Quantum Chromodynamics.…”