Quark helicity distributions in the nucleon for up, down, and strange quarks from semi-inclusive deep-inelastic scattering

Journal Article · Sat Jan 01 04:00:00 EST 2005 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PhysRevD.71.012003· OSTI ID:20705687

Airapetian, A; Akopov, N; Akopov, Z; Avakian, R; Avetissian, A; Elbakian, G; Gharibyan, V; Marukyan, H; Rostomyan, A; Taroian, S; Zohrabian, H ^[1]; Amarian, M ^[2]; Ammosov, V V; Bryzgalov, V; Gapienko, G; Gapienko, V; Ivanilov, A; Salomatin, Y; Tchuiko, B ^[3]; Andrus, A ^[4]

---

1. Yerevan Physics Institute, 375036 Yerevan (Armenia)
2. DESY Zeuthen, 15738 Zeuthen (Germany)
3. Institute for High Energy Physics, Protvino, Moscow region, 142281 (Russian Federation)
4. Department of Physics, University of Illinois, Urbana, Illinois 61801-3080 (United States); and others

Polarized deep-inelastic scattering data on longitudinally polarized hydrogen and deuterium targets have been used to determine double-spin asymmetries of cross sections. Inclusive and semi-inclusive asymmetries for the production of positive and negative pions from hydrogen were obtained in a reanalysis of previously published data. Inclusive and semi-inclusive asymmetries for the production of negative and positive pions and kaons were measured on a polarized deuterium target. The separate helicity densities for the up and down quarks and the anti-up, anti-down, and strange sea quarks were computed from these asymmetries in a ''leading order'' QCD analysis. The polarization of the up-quark is positive and that of the down-quark is negative. All extracted sea quark polarizations are consistent with zero, and the light quark sea helicity densities are flavor symmetric within the experimental uncertainties. First and second moments of the extracted quark helicity densities in the measured range are consistent with fits of inclusive data.

• OSTI ID: 20705687
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 1 Vol. 71; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ASYMMETRY
D QUARKS
DEEP INELASTIC SCATTERING
DEUTERIUM TARGET
DISTRIBUTION
HELICITY
HYDROGEN 1 TARGET
KAONS
NUCLEONS
PARTICLE PRODUCTION
PARTICLE STRUCTURE
PIONS
POLARIZATION
POLARIZED TARGETS
QUANTUM CHROMODYNAMICS
S QUARKS
SPIN
U QUARKS