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Article
Report number arXiv:1007.4061 ; CERN-PH-EP-2010-023 ; CERN-PH-EP-2010-023
Title Quark helicity distributions from longitudinal spin asymmetries in muon-proton and muon-deuteron scattering
Author(s) COMPASS Collaboration  Show all 218 authors
Publication 2010
Imprint 21 Jul 2010
Number of pages 13
Note Comments: 13 pages, 5 figures
13 pages, 5 figures
In: Phys. Lett. B 693 (2010) 227-235
DOI 10.1016/j.physletb.2010.08.034
Subject category Particle Physics - Experiment ; Particle Physics - Experiment
Accelerator/Facility, Experiment CERN SPS ; COMPASS NA58
Free keywords COMPASS ; semi-inclusive deep inelastic scattering ; spin ; structure function ; parton distribution functions
Abstract Double-spin asymmetries for production of charged pions and kaons in semi-inclusive deep-inelastic muon scattering have been measured by the COMPASS experiment at CERN. The data, obtained by scattering a 160 GeV muon beam off a longitudinally polarised NH_3 target, cover a range of the Bjorken variable x between 0.004 and 0.7. A leading order evaluation of the helicity distributions for the three lightest quarks and antiquark flavours derived from these asymmetries and from our previous deuteron data is presented. The resulting values of the sea quark distributions are small and do not show any sizable dependence on x in the range of the measurements. No significant difference is observed between the strange and antistrange helicity distributions, both compatible with zero. The integrated value of the flavour asymmetry of the helicity distribution of the light-quark sea, \Delta u-bar - \Delta d-bar, is found to be slightly positive, about 1.5 standard deviations away from zero.
Copyright/License Preprint: © 2010-2025 CERN (License: CC-BY-3.0)

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Email contact: gerhard.mallot@cern.ch


 Record created 2010-07-23, last modified 2023-02-08


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