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Article
Report number arXiv:1612.00620 ; CERN-EP-2016-299
Title Final COMPASS results on the deuteron spin-dependent structure function g1d and the Bjorken sum rule
Author(s) COMPASS Collaboration  Prikaži svih 228 autora
Publication 2017-06-10
Imprint 2016-12-02
Number of pages 8
Note 16 pages, 6 figures
In: Phys. Lett. B 769 (2017) 34-41
DOI 10.1016/j.physletb.2017.03.018
Subject category hep-ex ; Particle Physics - Experiment
Accelerator/Facility, Experiment CERN SPS ; COMPASS NA58
Free keywords QCD ; polarization ; experimental results ; COMPASS ; deep inelastic scattering ; spin ; structure function ; parton helicity distributions
Abstract Final results are presented from the inclusive measurement of deep-inelastic polarised-muon scattering on longitudinally polarised deuterons using a 6LiD target. The data were taken at 160GeV beam energy and the results are shown for the kinematic range 1(GeV/c)2<Q2<100(GeV/c)2 in photon virtuality, 0.004<x<0.7 in the Bjorken scaling variable and W>4GeV/c2 in the mass of the hadronic final state. The deuteron double-spin asymmetry A1d and the deuteron longitudinal-spin structure function g1d are presented in bins of x and Q2. Towards lowest accessible values of x, g1d decreases and becomes consistent with zero within uncertainties. The presented final g1d values together with the recently published final g1p values of COMPASS are used to again evaluate the Bjorken sum rule and perform the QCD fit to the g1 world data at next-to-leading order of the strong coupling constant. In both cases, changes in central values of the resulting numbers are well within statistical uncertainties. The flavour-singlet axial charge a0, {which is identified in the MS¯ renormalisation scheme with the total contribution of quark helicities to the nucleon spin}, is extracted from only the COMPASS deuteron data with negligible extrapolation uncertainty: a0(Q2=3(GeV/c)2)=0.32±0.02stat±0.04syst±0.05evol. Together with the recent results on the proton spin structure function g1p, the results on g1d constitute the COMPASS legacy on the measurements of g1 through inclusive spin-dependent deep inelastic scattering.
Copyright/License arXiv nonexclusive-distrib. 1.0
preprint: © 2016-2025 CERN (License: CC-BY-4.0)
publication: © 2017-2025 The Author(s) (License: CC-BY-4.0), sponsored by SCOAP³



Corresponding record in: Inspire
Email contact: oleg.denisov@cern.ch


 Zapis kreiran 2016-12-07, zadnja izmjena 2024-07-20


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