Precision measurement of the neutron spin asymmetry A{sub 1}{sup n} and spin-flavor decomposition in the valence quark region

Journal Article · Thu Jan 08 23:00:00 EST 2004 · Physical Review Letters

OSTI ID:834982

Zheng, Xiaochao

We have measured the neutron spin asymmetry A{sub 1}{sup n} with high precision at three kinematics in the deep inelastic region at x = 0.33, 0.47 and 0.60, and Q{sup 2} = 2.7, 3.5 and 4.8 (GeV/c){sup 2}, respectively. Our results unambiguously show, for the first time, that A{sub 1}{sup n} crosses zero around x = 0.47 and becomes significantly positive at x = 0.60. Combined with the world proton data, polarized quark distributions were extracted. Our results, in general, agree with relativistic constituent quark models and with perturbative quantum chromodynamics (pQCD) analyses based on the earlier data. However they deviate from pQCD predictions based on hadron helicity conservation.

• Research Organization: Thomas Jefferson National Accelerator Facility, Newport News, VA (US)
• Sponsoring Organization: USDOE Office of Energy Research (ER) (US)
• DOE Contract Number: AC05-84ER40150
• OSTI ID: 834982
• Report Number(s): JLAB-PHY-03-62; DOE/ER/40150-3028; nucl-ex/0308011
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Vol. 92; ISSN 0031-9007; ISSN PRLTAO
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ACCURACY
ASYMMETRY
HADRONS
HELICITY
NEUTRONS
PROTONS
QUANTUM CHROMODYNAMICS
QUARK MODEL
QUARKS
SPIN
VALENCE