Nucleon spin structure and perturbative QCD frontier on the move

Journal Article · Fri Jan 01 00:00:00 EST 2010 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.81.016010· OSTI ID:21409012

Pasechnik, Roman S; Shirkov, Dmitry V; Teryaev, Oleg V; Solovtsova, Olga P; Khandramai, Vyacheslav L ^[1]

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1. High Energy Physics, Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala (Sweden)

We discuss the interplay between higher orders of the perturbative QCD expansion and higher-twist contributions in the analysis of recent Jefferson Lab data on the lowest moments of spin-dependent proton and neutron structure functions {Gamma}{sub 1}{sup p,n}(Q{sup 2}) and Bjorken sum rule function {Gamma}{sub 1}{sup p-n}(Q{sup 2}) at 0.05<Q{sup 2}<3 GeV{sup 2}. We demonstrate that the values of the higher-twist coefficients {mu}{sub 2k}{sup p,n} extracted from the mentioned data by using the singularity-free analytic perturbation theory provide a better convergence of the higher-twist series than with the standard perturbative QCD. From the high-precision proton data, we extract the value of the singlet axial charge a{sub 0}(1 GeV{sup 2})=0.33{+-}0.05. We observe a slow Q{sup 2} dependence of fitted values of the twist coefficient {mu}{sub 4} and a{sub 0} when going to lower energy scales, which can be explained by the well-known renormalization group evolution of {mu}{sub 4}(Q{sup 2}) and a{sub 0}(Q{sup 2}). As the main result, a good quantitative description of all the Jefferson Lab data sets down to Q{approx_equal}350 MeV is achieved.

• OSTI ID: 21409012
• Journal Information: Physical Review. D, Particles Fields, Vol. 81, Issue 1; Other Information: DOI: 10.1103/PhysRevD.81.016010; (c) 2010 The American Physical Society; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
CEBAF ACCELERATOR
MEV RANGE 100-1000
NEUTRONS
PERTURBATION THEORY
PROTONS
QUANTUM CHROMODYNAMICS
RENORMALIZATION
SINGULARITY
SPIN
STRUCTURE FUNCTIONS
SUM RULES
ACCELERATORS
ANGULAR MOMENTUM
BARYONS
ELEMENTARY PARTICLES
ENERGY RANGE
EQUATIONS
FERMIONS
FIELD THEORIES
FUNCTIONS
HADRONS
LINEAR ACCELERATORS
MEV RANGE
NUCLEONS
PARTICLE PROPERTIES
QUANTUM FIELD THEORY