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Gluon-spin contribution to the proton spin from the double helicity asymmetry in inclusive pi0 production in polarized p + p collisions at s**(1/2) = 200 GeV

SYSNO ASEP	0345166
Document Type	J - Journal Article
R&D Document Type	Journal Article
Subsidiary J	Článek ve WOS
Title	Gluon-spin contribution to the proton spin from the double helicity asymmetry in inclusive pi0 production in polarized p + p collisions at s**(1/2) = 200 GeV
Author(s)	Adare, A. (US) Afanasiev, S. (RU) Aidala, C. (US) Růžička, Pavel (FZU-D) Tomášek, Lukáš (FZU-D)_{RID, ORCID} Vrba, Václav (FZU-D)_{RID, ORCID}
Source Title	Physical Review Letters. - : American Physical Society - ISSN 0031-9007 Roč. 103, č. 1 (2009), 012003/1-012003/4
Number of pages	4 s.
Language	eng - English
Country	US - United States
Keywords	PHENIX ; gluon ; proton spin
Subject RIV	BF - Elementary Particles and High Energy Physics
R&D Projects	LA08015 GA MŠMT - Ministry of Education, Youth and Sports (MEYS)
CEZ	AV0Z10100502 - FZU-D (2005-2011)
UT WOS	000267697900014
DOI	10.1103/PhysRevLett.103.012003
Annotation	he double helicity asymmetry in neutral pion production for p_T = 1 to 12 GeV/c has been measured with the PHENIX experiment in order to access the gluon spin contribution, Delta-G, to the proton spin. Measured asymmetries are consistent with zero, and at a theory scale of /mu^2 = 4 GeV^2 give Delta-G^[0.02,0.3] = 0.1 to 0.2, with a constraint of -0.7 < Delta-G^[0.02,0.3] < 0.5 at Delta-chi^2 = 9 (~3 sigma) for our sampled gluon momentum fraction (x) range, 0.02 to 0.3. The results are obtained using predictions for our measured asymmetries generated from four representative fits to polarized deep inelastic scattering data. We also consider the dependence of the Delta-G constraint on the choice of theoretical scale, a dominant uncertainty in these predictions.
Workplace	Institute of Physics
Contact	Kristina Potocká, potocka@fzu.cz, Tel.: 220 318 579
Year of Publishing	2011

Number of the records: 1